Records |
Author |
Zhang, L.-F.; Covaci, L.; Peeters, F.M. |
Title |
Tomasch effect in nanoscale superconductors |
Type |
A1 Journal article |
Year |
2015 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
Volume |
91 |
Issue |
91 |
Pages |
024508 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
The Tomasch effect (TE) is due to quasiparticle interference (QPI) as induced by a nonuniform superconducting order parameter, which results in oscillations in the density of states (DOS) at energies above the superconducting gap. Quantum confinement in nanoscale superconductors leads to an inhomogenerous distribution of the Cooperpair condensate, which, as we found, triggers the manifestation of a new TE. We investigate the electronic structure of nanoscale superconductors by solving the Bogoliubov-de Gennes (BdG) equations self-consistently and describe the TE determined by two types of processes, involving two-or three-subband QPIs. Both types of QPIs result in additional BCS-like Bogoliubov-quasiparticles and BCS-like energy gaps leading to oscillations in the DOS and modulated wave patterns in the local density of states. These effects are strongly related to the symmetries of the system. A reduced 4 x 4 inter-subband BdG Hamiltonian is established in order to describe analytically the TE of two-subband QPIs. Our study is relevant to nanoscale superconductors, either nanowires or thin films, Bose-Einsten condensates, and confined systems such as two-dimensional electron gas interface superconductivity. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Lancaster, Pa |
Editor |
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Language |
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Wos |
000348473700003 |
Publication Date |
2015-01-16 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
|
ISSN |
1098-0121;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
3.836 |
Times cited |
6 |
Open Access |
|
Notes |
; This work was supported by the Flemish Science Foundation (FWO-Vlaanderen) and the Methusalem funding of the Flemish Government. ; |
Approved |
Most recent IF: 3.836; 2015 IF: 3.736 |
Call Number |
c:irua:123864 |
Serial |
3670 |
Permanent link to this record |
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Author |
Schoelz, J.K.; Xu, P.; Meunier, V.; Kumar, P.; Neek-Amal, M.; Thibado, P.M.; Peeters, F.M. |
Title |
Graphene ripples as a realization of a two-dimensional Ising model : a scanning tunneling microscope study |
Type |
A1 Journal article |
Year |
2015 |
Publication |
Physical review: B: condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
Volume |
91 |
Issue |
91 |
Pages |
045413 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
Ripples in pristine freestanding graphene naturally orient themselves in an array that is alternately curved-up and curved-down; maintaining an average height of zero. Using scanning tunneling microscopy (STM) to apply a local force, the graphene sheet will reversibly rise and fall in height until the height reaches 60%-70% of its maximum at which point a sudden, permanent jump occurs. We successfully model the ripples as a spin-half Ising magnetic system, where the height of the graphene plays the role of the spin. The permanent jump in height, controlled by the tunneling current, is found to be equivalent to an antiferromagnetic-to-ferromagnetic phase transition. The thermal load underneath the STM tip alters the local tension and is identified as the responsible mechanism for the phase transition. Four universal critical exponents are measured from our STM data, and the model provides insight into the statistical role of graphene's unusual negative thermal expansion coefficient. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Lancaster, Pa |
Editor |
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Language |
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Wos |
000348762200011 |
Publication Date |
2015-01-12 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1098-0121;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
3.836 |
Times cited |
21 |
Open Access |
|
Notes |
; This work was supported in part by Office of Naval Research (USA) under Grant No. N00014-10-1-0181 and National Science Foundation (USA) under Grant No. DMR-0855358. F. M. Peeters and M. Neek-Amal were supported by the Flemish Science Foundation (FWO-Vl) and the Methusalem Foundation of the Flemish Government. ; |
Approved |
Most recent IF: 3.836; 2015 IF: 3.736 |
Call Number |
c:irua:123866 |
Serial |
1377 |
Permanent link to this record |
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Author |
Hai, G.-Q.; Peeters, F.M. |
Title |
Hamiltonian of a many-electron system with single-electron and electron-pair states in a two-dimensional periodic potential |
Type |
A1 Journal article |
Year |
2015 |
Publication |
European physical journal : B : condensed matter and complex systems |
Abbreviated Journal |
Eur Phys J B |
Volume |
88 |
Issue |
88 |
Pages |
20 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
Based on the metastable electron-pair energy band in a two-dimensional (2D) periodic potential obtained previously by Hai and Castelano [J. Phys.: Condens. Matter 26, 115502 (2014)], we present in this work a Hamiltonian of many electrons consisting of single electrons and electron pairs in the 2D system. The electron-pair states are metastable of energies higher than those of the single-electron states at low electron density. We assume two different scenarios for the single-electron band. When it is considered as the lowest conduction band of a crystal, we compare the obtained Hamiltonian with the phenomenological model Hamiltonian of a boson-fermion mixture proposed by Friedberg and Lee [Phys. Rev. B 40, 6745 (1989)]. Single-electron-electron-pair and electron-pair-electron-pair interaction terms appear in our Hamiltonian and the interaction potentials can be determined from the electron-electron Coulomb interactions. When we consider the single-electron band as the highest valence band of a crystal, we show that holes in this valence band are important for stabilization of the electron-pair states in the system. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Berlin |
Editor |
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Language |
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Wos |
000347776800005 |
Publication Date |
2015-01-10 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
|
Edition |
|
ISSN |
1434-6028;1434-6036; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
1.461 |
Times cited |
2 |
Open Access |
|
Notes |
; This work was supported by FAPESP and CNPq (Brazil). ; |
Approved |
Most recent IF: 1.461; 2015 IF: 1.345 |
Call Number |
c:irua:125317 |
Serial |
1406 |
Permanent link to this record |
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Author |
Bacaksiz, C.; Sahin, H.; Ozaydin, H.D.; Horzum, S.; Senger, R.T.; Peeters, F.M. |
Title |
Hexagonal A1N : dimensional-crossover-driven band-gap transition |
Type |
A1 Journal article |
Year |
2015 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
Volume |
91 |
Issue |
91 |
Pages |
085430 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
Motivated by a recent experiment that reported the successful synthesis of hexagonal (h) AlN [Tsipas et al., Appl. Phys. Lett. 103, 251605 (2013)], we investigate structural, electronic, and vibrational properties of bulk, bilayer, and monolayer structures of h-AlN by using first-principles calculations. We show that the hexagonal phase of the bulk h-AlN is a stable direct-band-gap semiconductor. The calculated phonon spectrum displays a rigid-layer shear mode at 274 cm(-1) and an E-g mode at 703 cm(-1), which are observable by Raman measurements. In addition, single-layer h-AlN is an indirect-band-gap semiconductor with a nonmagnetic ground state. For the bilayer structure, AA'-type stacking is found to be the most favorable one, and interlayer interaction is strong. While N-layered h-AlN is an indirect-band-gap semiconductor for N = 1 – 9, we predict that thicker structures (N >= 10) have a direct band gap at the Gamma point. The number-of-layer-dependent band-gap transitions in h-AlN is interesting in that it is significantly different from the indirect-to-direct crossover obtained in the transition-metal dichalcogenides. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000350319200020 |
Publication Date |
2015-02-27 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
|
Edition |
|
ISSN |
1098-0121;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
3.836 |
Times cited |
99 |
Open Access |
|
Notes |
; This work was supported by the Flemish Science Foundation (FWO-Vl) and the Methusalem foundation of the Flemish government. Computational resources were provided by TUBITAK ULAKBIM, High Performance and Grid Computing Center (TR-Grid e-Infrastructure). C.B. and R.T.S. acknowledge the support from TUBITAK Project No 114F397. H.S. is supported by a FWO Pegasus Long Marie Curie Fellowship. ; |
Approved |
Most recent IF: 3.836; 2015 IF: 3.736 |
Call Number |
c:irua:125416 |
Serial |
1421 |
Permanent link to this record |
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Author |
Petrovic, M.D.; Peeters, F.M. |
Title |
Fano resonances in the conductance of graphene nanoribbons with side gates |
Type |
A1 Journal article |
Year |
2015 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
Volume |
91 |
Issue |
91 |
Pages |
035444 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
The control of side gates on the quantum electron transport in narrow graphene ribbons of different widths and edge types (armchair and zigzag) is investigated. The conductance exhibits Fano resonances with varying side gate potential. Resonant and antiresonant peaks in the conductance can be associated with the eigenstates of a closed system, and these peaks can be accurately fitted with a Fano line shape. The local density of states (LDOS) and the electron current show a specific behavior at these resonances, which depends on the ribbon edge type. In zigzag ribbons, transport is dominated by intervalley scattering, which is reflected in the transmission functions of individual modes. The side gates induce p-n interfaces near the edges at which the LDOS exhibits peaks. Near the resonance points, the electron current flows uniformly through the constriction, while near the antiresonances it creates vortices. In the armchair ribbons the LDOS spreads in areas of high potential, with current flowing near the edges. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000351217900005 |
Publication Date |
2015-01-30 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1098-0121;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
3.836 |
Times cited |
17 |
Open Access |
|
Notes |
; This work was supported by the Methusalem programme of the Flemish government. ; |
Approved |
Most recent IF: 3.836; 2015 IF: 3.736 |
Call Number |
c:irua:125422 |
Serial |
1172 |
Permanent link to this record |
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Author |
Chen, Y.; Hong-Yu, W.; Peeters, F.M.; Shanenko, A.A. |
Title |
Quantum-size effects and thermal response of anti-Kramer-Pesch vortex core |
Type |
A1 Journal article |
Year |
2015 |
Publication |
Journal of physics : condensed matter |
Abbreviated Journal |
J Phys-Condens Mat |
Volume |
27 |
Issue |
27 |
Pages |
125701 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
Since the 1960's it has been well known that the basic superconductive quantities can exhibit oscillations as functions of the thickness (diameter) in superconducting nanofilms (nanowires) due to the size quantization of the electronic spectrum. However, very little is known about the effects of quantum confinement on the microscopic properties of vortices. Based on a numerical solution to the Bogoliubov-de Gennes equations, we study the quantum-size oscillations of the vortex core resulting from the sequential interchange of the Kramer-Pesch and anti-Kramer-Pesch regimes with changing nanocylinder radius. The physics behind the anti-Kramer-Pesch anomaly is displayed by utilizing a semi-analytical Anderson approximate solution. We also demonstrate that the anti-Kramer-Pesch vortex core is robust against thermal smearing and results in a distinctive two-maxima structure in the local density of states, which can be used to identify the existence of the anti-Kramer-Pesch vortex. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
London |
Editor |
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Language |
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Wos |
000351294700018 |
Publication Date |
2015-03-09 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0953-8984;1361-648X; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
2.649 |
Times cited |
4 |
Open Access |
|
Notes |
; This work was supported by the National Natural Science Foundation of China under Grant No. NSFC-11304134, the Flemish Science Foundation (FWO-Vl), and the Methusalem program. AAS acknowledges the support of the Brazilian agencies CNPq (grants 307552/2012-8 and 141911/2012-3) and FACEPE (APQ-0589-1.05/08). WHY acknowledges the support of Scientific Research Fund of Zhejiang Provincial Education Department (Y201120994). ; |
Approved |
Most recent IF: 2.649; 2015 IF: 2.346 |
Call Number |
c:irua:125460 |
Serial |
2787 |
Permanent link to this record |
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Author |
Leenaerts, O.; Schoeters, B.; Partoens, B. |
Title |
Stable kagome lattices from group IV elements |
Type |
A1 Journal article |
Year |
2015 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
Volume |
91 |
Issue |
91 |
Pages |
115202 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
A thorough investigation of three-dimensional kagome lattices of group IV elements is performed with first-principles calculations. The investigated kagome lattices of silicon and germanium are found to be of similar stability as the recently proposed carbon kagome lattice. Carbon and silicon kagome lattices are both direct-gap semiconductors but they have qualitatively different electronic band structures. While direct optical transitions between the valence and conduction bands are allowed in the carbon case, no such transitions can be observed for silicon. The kagome lattice of germanium exhibits semimetallic behavior but can be transformed into a semiconductor after compression. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000351900700003 |
Publication Date |
2015-03-10 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1098-0121;1550-235X; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
3.836 |
Times cited |
12 |
Open Access |
|
Notes |
; This work was supported by the Fonds Wetenschappelijk Onderzoek (FWO-Vl). The computational resources and services used in this work were provided by the VSC (Flemish Supercomputer Center), funded by the Hercules Foundation and the Flemish Government – department EWI. ; |
Approved |
Most recent IF: 3.836; 2015 IF: 3.736 |
Call Number |
c:irua:125516 |
Serial |
3144 |
Permanent link to this record |
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Author |
Zalipaev, V.; Linton, C.M.; Croitoru, M.D.; Vagov, A. |
Title |
Resonant tunneling and localized states in a graphene monolayer with a mass gap |
Type |
A1 Journal article |
Year |
2015 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
Volume |
91 |
Issue |
91 |
Pages |
085405 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
We study tunneling of quasiparticles through potential barriers in a graphene monolayer with the mass gap using a semiclassical (WKB) approach. The main equations are derived in away similar to the WKB theory for the Schrodinger equation, which allows for explicit solutions at all orders. The analog of the classical action is used to distinguish types of possible stationary states in the system. The analysis focuses on the resonant scattering and the hole states localized in the vicinity of a barrier that are often overlooked. The scattering coefficients for the physically interesting limits are obtained by matching the WKB approximation with the known solutions at turning points. The localized states demonstrate unconventional properties and lead to alterations of the single particle density of states. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000351773900004 |
Publication Date |
2015-02-05 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1098-0121;1550-235X; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
3.836 |
Times cited |
3 |
Open Access |
|
Notes |
; M.D.C. acknowledges the Belgian Science Policy (BELSPO Back to Belgium Grant). ; |
Approved |
Most recent IF: 3.836; 2015 IF: 3.736 |
Call Number |
c:irua:125523 |
Serial |
2891 |
Permanent link to this record |
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Author |
Vasylenko, A.A.; Misko, V.R. |
Title |
Nonlinear transport of the Wigner crystal in symmetric and asymmetric FET-like structures : nonlinear transport of the Wigner crystal on superfluid He-4 in quasi-one-dimensional channels with symmetric and asymmetric constrictions |
Type |
A1 Journal article |
Year |
2015 |
Publication |
European physical journal : B : condensed matter and complex systems |
Abbreviated Journal |
Eur Phys J B |
Volume |
88 |
Issue |
88 |
Pages |
105 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
When floating on a two-dimensional surface of superfluid He-4, electrons arrange themselves in two-dimensional crystalline structure known as Wigner crystal. In channels, the boundaries interfere the crystalline order and in case of very narrow channels one observes a quasi-one-dimensional (quasi-1D) Wigner crystal formed by just a few rows of electrons and, ultimately, one row in the “quantum wire” regime. Recently, the “quantum wire” regime was accessed experimentally [D.G. Rees, H. Totsuji, K. Kono, Phys. Rev. Lett. 108, 176801 (2012)] resulting in unusual transport phenomena such as, e.g., oscillations in the electron conductance. Using molecular dynamics simulations, we study the nonlinear transport of electrons in channels with various types of constrictions: single and multiple symmetric and asymmetric geometrical constrictions with varying width and length, and saddle-point-type potentials with varying gate voltage. In particular, we analyze the average particle velocity of the particles and the corresponding electron current versus the driving force or the gate voltage. We have revealed a significant difference in the dynamics for long and short constrictions: The oscillations of the average velocity of the particles for the systems with short constrictions exhibit a clear correlation with the transitions between the states with different numbers of rows of particles; on the other hand, for the systems with longer constrictions these oscillations are suppressed. The obtained results qualitatively agree with the experimental observations. Next, we propose a FET-like structure that consists of a channel with asymmetric constrictions. We show that applying a transverse bias results either in increase of the average particle velocity or in its suppression thus allowing a flexible control tool over the electron transport. The advantage of the asymmetric FET is that it does not have a gate and it allows an easy control of relatively large electron flow. Furthermore, the asymmetric device can be used for rectification of an ac-driven electron flow. Our results bring important insights into the dynamics of electrons floating on the surface of superfluid He-4 in channels with constrictions and allow the effective control over the electron transport. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Berlin |
Editor |
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Language |
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Wos |
000353065100002 |
Publication Date |
2015-04-16 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
|
ISSN |
1434-6028;1434-6036; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
1.461 |
Times cited |
|
Open Access |
|
Notes |
|
Approved |
Most recent IF: 1.461; 2015 IF: 1.345 |
Call Number |
c:irua:125997 |
Serial |
2359 |
Permanent link to this record |
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Author |
Nishio, K.; Lu, A.K.A.; Pourtois, G. |
Title |
Low-strain Si/O superlattices with tunable electronic properties : ab initio calculations |
Type |
A1 Journal article |
Year |
2015 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
Volume |
91 |
Issue |
91 |
Pages |
165303 |
Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
Abstract |
We propose that low-strain Si/O superlattices can be constructed by connecting reconstructed Si{001} surfaces by Si-O-Si bridges. Ab initio calculations show that our models are energetically more favorable than all the models proposed so far. The part of our Si/O superlattice model is experimentally accessible just by oxidizing a Si( 001) substrate. To complete our Si/O superlattice model, we propose a three-step method. We also explore the potential of our Si/O superlattice models for new materials used in future Si electronics. We find that the location of the channel where the carriers travel can be controlled between the interfaces and the Si layers by the insertion of O atoms into the Si-Si dimers. By revealing the origins of the interface electron and hole states, we find that similar interface states should be easily achieved for Si slabs and Si substrates. Interestingly, the interface electrons and holes have small effective masses in the direction parallel to the channel and large effective masses in the direction normal to the channel, which makes the Si/O superlattices attractive to be used for channel materials. We also find that the valley splitting of Si is enhanced by the formation of the Si/O/Si interfaces, which is ideal for developing Si-based qubits. Our findings open new perspectives to design and control the electronic properties of Si. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000352986700002 |
Publication Date |
2015-04-16 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1098-0121;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
3.836 |
Times cited |
6 |
Open Access |
|
Notes |
|
Approved |
Most recent IF: 3.836; 2015 IF: 3.736 |
Call Number |
c:irua:125998 |
Serial |
1852 |
Permanent link to this record |
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Author |
Van de Put, M.L.; Vandenberghe, W.G.; Magnus, W.; Sorée, B. |
Title |
An envelope function formalism for lattice-matched heterostructures |
Type |
A1 Journal article |
Year |
2015 |
Publication |
Physica: B : condensed matter |
Abbreviated Journal |
Physica B |
Volume |
470-471 |
Issue |
470-471 |
Pages |
69-75 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
The envelope function method traditionally employs a single basis set which, in practice, relates to a single material because the k.p matrix elements are generally only known in a particular basis. In this work, we defined a basis function transformation to alleviate this restriction. The transformation is completely described by the known inter-band momentum matrix elements. The resulting envelope function equation can solve the electronic structure in lattice matched heterostructures without resorting to boundary conditions at the interface between materials, while all unit-cell averaged observables can be calculated as with the standard envelope function formalism. In the case of two coupled bands, this heterostructure formalism is equivalent to the standard formalism while taking position dependent matrix elements. (C) 2015 Elsevier B.V. All rights reserved |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Amsterdam |
Editor |
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Language |
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Wos |
000355149600011 |
Publication Date |
2015-04-26 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
|
ISSN |
0921-4526; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
1.386 |
Times cited |
5 |
Open Access |
|
Notes |
; ; |
Approved |
Most recent IF: 1.386; 2015 IF: 1.319 |
Call Number |
c:irua:126397 |
Serial |
95 |
Permanent link to this record |
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Author |
Shylau, A.A.; Badalyan, S.M.; Peeters, F.M.; Jauho, A.P. |
Title |
Electron polarization function and plasmons in metallic armchair graphene nanoribbons |
Type |
A1 Journal article |
Year |
2015 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
Volume |
91 |
Issue |
91 |
Pages |
205444 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
Plasmon excitations in metallic armchair graphene nanoribbons are investigated using the random phase approximation. An exact analytical expression for the polarization function of Dirac fermions is obtained, valid for arbitrary temperature and doping. We find that at finite temperatures, due to the phase space redistribution among inter-band and intra-band electronic transitions in the conduction and valence bands, the full polarization function becomes independent of temperature and position of the chemical potential. It is shown that for a given width of nanoribbon there exists a single plasmon mode whose energy dispersion is determined by the graphene's fine structure constant. In the case of two Coulomb-coupled nanoribbons, this plasmon splits into in-phase and out-of-phase plasmon modes with splitting energy determined by the inter-ribbon spacing. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000355315400007 |
Publication Date |
2015-05-29 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1098-0121 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
3.836 |
Times cited |
13 |
Open Access |
|
Notes |
; The Center for Nanostructured Graphene (CNG) is sponsored by the Danish National Research Foundation (DNRF58). The work at the University of Antwerp was supported by the Flemisch Science Foundation (FWO-Vl) and the Methusalem Foundation of the Flemish Government. S.M.B. gratefully acknowledges hospitality and support from the Department of Physics at the University of Missouri. ; |
Approved |
Most recent IF: 3.836; 2015 IF: 3.736 |
Call Number |
c:irua:126403 |
Serial |
984 |
Permanent link to this record |
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Author |
Szaszko-Bogar, V.; Peeters, F.M.; Foeldi, P. |
Title |
Oscillating spin-orbit interaction in two-dimensional superlattices : sharp transmission resonances and time-dependent spin-polarized currents |
Type |
A1 Journal article |
Year |
2015 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
Volume |
91 |
Issue |
91 |
Pages |
235311 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
We consider ballistic transport through a lateral, two-dimensional superlattice with experimentally realizable, sinusoidally oscillating, Rashba-type spin-orbit interaction (SOI). The periodic structure of the rectangular lattice produces a spin-dependent miniband structure for static SOI. Using Floquet theory, transmission peaks are shown to appear in themini-bandgaps as a consequence of the additional, time-dependent SOI. A detailed analysis shows that this effect is due to the generation of harmonics of the driving frequency, via which, e.g., resonances that cannot be excited in the case of static SOI become available. Additionally, the transmitted current shows space-and time-dependent partial spin polarization, in other words, polarization waves propagate through the superlattice. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000355956500003 |
Publication Date |
2015-06-10 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1098-0121;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
3.836 |
Times cited |
10 |
Open Access |
|
Notes |
; This work was partially supported by the European Union and the European Social Fund through Projects No. TAMOP-4.2.2.C-11/1/KONV-2012-0010 and No. TAMOP-4.2.2.A-11/1/KONV-2012-0060, and by the Hungarian Scientific Research Fund (OTKA) under Contracts No. T81364 and No. 116688. The ELI-ALPS Project (GOP-1.1.1-12/B-2012-0001) is supported by the European Union and cofinanced by the European Regional Development Fund. ; |
Approved |
Most recent IF: 3.836; 2015 IF: 3.736 |
Call Number |
c:irua:126432 |
Serial |
2534 |
Permanent link to this record |
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Author |
Zha, G.-Q.; Covaci, L.; Peeters, F.M.; Zhou, S.-P. |
Title |
Mixed pairing symmetries and flux-induced spin current in mesoscopic superconducting loops with spin correlations |
Type |
A1 Journal article |
Year |
2015 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
Volume |
91 |
Issue |
91 |
Pages |
214504 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
We numerically investigate the mixed pairing symmetries inmesoscopic superconducting loops in the presence of spin correlations by solving the Bogoliubov-de Gennes equations self-consistently. The spatial variations of the superconducting order parameters and the spontaneous magnetization are determined by the band structure. When the threaded magnetic flux turns on, the charge and spin currents both emerge and depict periodic evolution. In the case of a mesoscopic loop with dominant triplet p(x) +/- ip(y)-wave symmetry, a slight change of the chemical potential may lead to novel flux-dependent evolution patterns of the ground-state energy and the magnetization. The spin-polarized currents show pronounced quantum oscillations with fractional periods due to the appearance of energy jumps in flux, accompanied with a steplike feature of the enhanced spin current. Particularly, at some appropriate flux, the peaks of the zero-energy local density of states clearly indicate the occurrence of the odd-frequency pairing. In the case of a superconducting loop with dominant singlet d(x2-y2)-wave symmetry, the spatial profiles of the zero-energy local density of states and the magnetization show spin-dependent features on different sample diagonals. Moreover, the evolution of the flux-induced spin current always exhibits an hc/e periodicity. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000355647100003 |
Publication Date |
2015-06-05 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
|
ISSN |
1098-0121;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
3.836 |
Times cited |
15 |
Open Access |
|
Notes |
; This work was supported by the National Natural Science Foundation of China under Grants No. 61371020 and No. 61271163, by the Visiting Scholar Program of Shanghai Municipal Education Commission, and by the Flemish Science Foundation (FWO-Vl). ; |
Approved |
Most recent IF: 3.836; 2015 IF: 3.736 |
Call Number |
c:irua:126433 |
Serial |
2089 |
Permanent link to this record |
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Author |
Richardson, C.L.; Edkins, S.D.; Berdiyorov, G.R.; Chua, C.J.; Griffiths, J.P.; Jones, G.A.C.; Buitelaar, M.R.; Narayan, V.; Sfigakis, F.; Smith, C.G.; Covaci, L.; Connolly, M.R.; |
Title |
Vortex detection and quantum transport in mesoscopic graphene Josephson-junction arrays |
Type |
A1 Journal article |
Year |
2015 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
Volume |
91 |
Issue |
91 |
Pages |
245418 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
We investigate mesoscopic Josephson-junction arrays created by patterning superconducting disks on monolayer graphene, concentrating on the high-T/T-c regime of these devices and the phenomena which contribute to the superconducting glass state in diffusive arrays. We observe features in the magnetoconductance at rational fractions of flux quanta per array unit cell, which we attribute to the formation of flux-quantized vortices. The applied fields at which the features occur are well described by Ginzburg-Landau simulations that take into account the number of unit cells in the array. We find that the mean conductance and universal conductance fluctuations are both enhanced below the critical temperature and field of the superconductor, with greater enhancement away from the graphene Dirac point. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000356129800012 |
Publication Date |
2015-06-15 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
|
ISSN |
1098-0121;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
3.836 |
Times cited |
2 |
Open Access |
|
Notes |
; This work was financially supported by the Engineering and Physical Sciences Research Council, and an NPL/EPSRC Joint Postdoctoral Partnership. Supporting data for this paper is available at the DSpace@Cambridge data repository (https://www.repository.cam.ac.uk/handle/1810/248242). ; |
Approved |
Most recent IF: 3.836; 2015 IF: 3.736 |
Call Number |
c:irua:126982 |
Serial |
3865 |
Permanent link to this record |
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Author |
Aierken, Y.; Sahin, H.; Iyikanat, F.; Horzum, S.; Suslu, A.; Chen, B.; Senger, R.T.; Tongay, S.; Peeters, F.M. |
Title |
Portlandite crystal : bulk, bilayer, and monolayer structures |
Type |
A1 Journal article |
Year |
2015 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
Volume |
91 |
Issue |
91 |
Pages |
245413 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
Ca(OH)(2) crystals, well known as portlandite, are grown in layered form, and we found that they can be exfoliated on different substrates. We performed first principles calculations to investigate the structural, electronic, vibrational, and mechanical properties of bulk, bilayer, and monolayer structures of this material. Different from other lamellar structures such as graphite and transition-metal dichalcogenides, intralayer bonding in Ca(OH)(2) is mainly ionic, while the interlayer interaction remains a weak dispersion-type force. Unlike well-known transition-metal dichalcogenides that exhibit an indirect-to-direct band gap crossover when going from bulk to a single layer, Ca(OH)(2) is a direct band gap semiconductor independent of the number layers. The in-plane Young's modulus and the in-plane shear modulus of monolayer Ca(OH)(2) are predicted to be quite low while the in-plane Poisson ratio is larger in comparison to those in the monolayer of ionic crystal BN. We measured the Raman spectrum of bulk Ca(OH)(2) and identified the high-frequency OH stretching mode A(1g) at 3620 cm(-1). In this study, bilayer and monolayer portlandite [Ca(OH)(2)] are predicted to be stable and their characteristics are analyzed in detail. Our results can guide further research on ultrathin hydroxites. |
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Corporate Author |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000356135600007 |
Publication Date |
2015-06-12 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1098-0121;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
3.836 |
Times cited |
29 |
Open Access |
|
Notes |
; This work was supported by the Flemish Science Foundation (FWO-Vl) and the Methusalem foundation of the Flemish government. Computational resources were provided by TUBITAK ULAKBIM, High Performance and Grid Computing Center (TR-Grid e-Infrastructure). H.S. is supported by a FWO Pegasus Long Marie Curie Fellowship. ; |
Approved |
Most recent IF: 3.836; 2015 IF: 3.736 |
Call Number |
c:irua:126983 |
Serial |
2675 |
Permanent link to this record |
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Author |
Grujić, M.M.; Tadic, M.Z.; Peeters, F.M. |
Title |
Chiral properties of topological-state loops |
Type |
A1 Journal article |
Year |
2015 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
Volume |
91 |
Issue |
91 |
Pages |
245432 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
The angular momentum quantization of chiral gapless modes confined to a circularly shaped interface between two different topological phases is investigated. By examining several different setups, we show analytically that the angular momentum of the topological modes exhibits a highly chiral behavior, and can be coupled to spin and/or valley degrees of freedom, reflecting the nature of the interface states. A simple general one-dimensional model, valid for arbitrarily shaped loops, is shown to predict the corresponding energies and the magnetic moments. These loops can be viewed as building blocks for artificial magnets with tunable and highly diverse properties. |
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Corporate Author |
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Publisher |
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Place of Publication |
Lancaster, Pa |
Editor |
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Language |
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Wos |
000356928200005 |
Publication Date |
2015-06-27 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1098-0121;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
3.836 |
Times cited |
6 |
Open Access |
|
Notes |
; This work was supported by the Ministry of Education, Science and Technological Development (Serbia), and the Fonds Wetenschappelijk Onderzoek (Belgium). ; |
Approved |
Most recent IF: 3.836; 2015 IF: 3.736 |
Call Number |
c:irua:127039 |
Serial |
357 |
Permanent link to this record |
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Author |
Shakouri, K.; Peeters, F.M. |
Title |
Spin- and pseudospin-polarized quantum Hall liquids in HgTe quantum wells |
Type |
A1 Journal article |
Year |
2015 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
Volume |
92 |
Issue |
92 |
Pages |
045416 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
A Hg(Cd)Te insulator heterostructure hosts a two-dimensional electron system that can simulate the physics of Dirac fermions with only a single valley. We investigate the magnetotransport properties of this structure and show that, unlike most two-dimensional crystals with spin and valley coupled levels, the Shubnikov-de Haas oscillations exhibit a high spin polarization in the absence of any valley degree of freedom. This effect can be observed using magnetospectroscopy measurements for quantum well thicknesses corresponding to either the topologically trivial or quantum spin Hall phases. The pseudospin texture of the electrons near the Fermi level is also studied and we show that a tunable pseudospin-polarized quantum Hall liquid can only be observed for thicknesses corresponding to the inverted regime. |
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Publisher |
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Place of Publication |
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Wos |
000358032000002 |
Publication Date |
2015-07-17 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1098-0121;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
3.836 |
Times cited |
3 |
Open Access |
|
Notes |
; This work was supported by the Flemish Science Foundation (FWO-Vl) and the Methusalem program of the Flemish government. ; |
Approved |
Most recent IF: 3.836; 2015 IF: 3.736 |
Call Number |
c:irua:127097 |
Serial |
3077 |
Permanent link to this record |
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Author |
Shakouri, K.; Simchi, H.; Esmaeilzadeh, M.; Mazidabadi, H.; Peeters, F.M. |
Title |
Tunable spin and charge transport in silicene nanoribbons |
Type |
A1 Journal article |
Year |
2015 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
Volume |
92 |
Issue |
92 |
Pages |
035413 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
Using the tight-binding formalism, we study spin and charge transport through a zigzag silicene ribbon subject to an external electric field E-z. The effect of an exchange field M-z is also taken into account and its consequences on the band structure as well as spin transport are evaluated. We show that the band structure lacks spin inversion symmetry in the presence of intrinsic spin-orbit interaction in combination of E-z and M-z fields. Our quantum transport calculations indicate that for certain energy ranges of the incoming electrons the silicene ribbon can act as a controllable high-efficiency spin polarizer. The polarization maxima occur simultaneously with the van Hove singularities of the local density of states. In this case, the combination of electric and exchange fields is the key to achieving nearly perfect spin polarization, which also leads to the appearance of additional narrow plateaus in the quantum conductance. Moreover, we demonstrate that the output current still remains completely spin-polarized for low-energy carriers even when a few edge vacancies are present. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000357806900004 |
Publication Date |
2015-07-10 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1098-0121;1550-235X; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
3.836 |
Times cited |
70 |
Open Access |
|
Notes |
; ; |
Approved |
Most recent IF: 3.836; 2015 IF: 3.736 |
Call Number |
c:irua:127099 |
Serial |
3746 |
Permanent link to this record |
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Author |
da Costa, D.R.; Chaves, A.; Sena, S.H.R.; Farias, G.A.; Peeters, F.M. |
Title |
Valley filtering using electrostatic potentials in bilayer graphene |
Type |
A1 Journal article |
Year |
2015 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
Volume |
92 |
Issue |
92 |
Pages |
045417 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
Propagation of an electron wave packet through a quantum point contact (QPC) defined by electrostatic gates in bilayer graphene is investigated. The gates provide a bias between the layers, in order to produce an energy gap. If the gates on both sides of the contact produce the same bias, steps in the electron transmission probability are observed, as in the usual QPC. However, if the bias is inverted on one of the sides of the QPC, only electrons belonging to one of the Dirac valleys are allowed to pass, which provides a very efficient valley filtering. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000358253200009 |
Publication Date |
2015-07-20 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1098-0121;1550-235X; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
3.836 |
Times cited |
47 |
Open Access |
|
Notes |
; This work was financially supported by CNPq, under PNPD and PRONEX/FUNCAP grants; the CAPES Foundation under ProcessNo. BEX7178/13-1; the Bilateral programme between Flanders and Brazil; the Flemish Science Foundation (FWOVl); and the Brazilian program Science Without Borders (CsF). ; |
Approved |
Most recent IF: 3.836; 2015 IF: 3.736 |
Call Number |
c:irua:127152 |
Serial |
3833 |
Permanent link to this record |
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Author |
Tahir, M.; Vasilopoulos, P.; Peeters, F.M. |
Title |
Magneto-optical transport properties of monolayer phosphorene |
Type |
A1 Journal article |
Year |
2015 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
Volume |
92 |
Issue |
92 |
Pages |
045420 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
The electronic properties of monolayer phosphorene are exotic due to its puckered structure and large intrinsic direct band gap. We derive and discuss its band structure in the presence of a perpendicular magnetic field. Further, we evaluate the magneto-optical Hall and longitudinal optical conductivities as functions of temperature, magnetic field, and Fermi energy, and show that they are strongly influenced by the magnetic field. The imaginary part of the former and the real part of the latter exhibit regular interband oscillations as functions of the frequency omega in the range (h) over bar omega similar to 1.5-2 eV. Strong intraband responses in the latter and weak ones in the former occur at much lower frequencies. The magneto-optical response can be tuned in the microwave-to-terahertz and visible frequency ranges in contrast with a conventional two-dimensional electron gas or graphene in which the response is limited to the terahertz regime. This ability to isolate carriers in an anisotropic structure may make phosphorene a promising candidate for new optical devices. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000358373600003 |
Publication Date |
2015-07-23 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1098-0121;1550-235X; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
3.836 |
Times cited |
68 |
Open Access |
|
Notes |
; This work was supported by the the Canadian NSERC Grant No. OGP0121756 (M.T., P.V.) and by the Flemish Science Foundation (FWO-Vl) (F.M.P.). ; |
Approved |
Most recent IF: 3.836; 2015 IF: 3.736 |
Call Number |
c:irua:127192 |
Serial |
1903 |
Permanent link to this record |
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Author |
Aierken, Y.; Çakır, D.; Sevik, C.; Peeters, F.M. |
Title |
Thermal properties of black and blue phosphorenes from a first-principles quasiharmonic approach |
Type |
A1 Journal article |
Year |
2015 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
Volume |
92 |
Issue |
92 |
Pages |
081408 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
Different allotropes of phosphorene are possible of which black and blue phosphorus are the most stable. While blue phosphorus has isotropic properties, black phosphorus is strongly anisotropic in its electronic and optical properties due to its anisotropic crystal structure. In this work, we systematically investigated the lattice thermal properties of black and blue phosphorene by using first-principles calculations based on the quasiharmonic approximation approach. Similar to the optoelectronic and electronic properties, we predict that black phosphorene has highly anisotropic thermal properties, in contrast to the blue phase. The linear thermal expansion coefficients along the zigzag and armchair direction differ up to 20% in black phosphorene. The armchair direction of black phosphorene is more expandable as compared to the zigzag direction and the biaxial expansion of blue phosphorene under finite temperature. Our comparative analysis reveals that the inclusion of finite-temperature effects makes the blue phase thermodynamically more stable over the black phase above 135 K. |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000359860700005 |
Publication Date |
2015-08-19 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1098-0121 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
3.836 |
Times cited |
124 |
Open Access |
|
Notes |
This work was supported by the Flemish Science Founda- tion (FWO-Vl) and the Methusalem foundation of the Flem- ish government. Computational resources were provided by TUBITAK ULAKBIM, High Performance and Grid Comput- ing Center (TR-Grid e-Infrastructure), and HPC infrastructure of the University of Antwerp (CalcUA), a division of the Flemish Supercomputer Center (VSC), which is funded by the Hercules foundation. C.S. acknowledges the support from Anadolu University (BAP-1407F335), and Turkish Academy of Sciences (TUBA-GEBIP). |
Approved |
Most recent IF: 3.836; 2015 IF: 3.736 |
Call Number |
c:irua:127754 |
Serial |
4034 |
Permanent link to this record |
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Author |
Aierken, Y.; Leenaerts, O.; Peeters, F.M. |
Title |
Defect-induced faceted blue phosphorene nanotubes |
Type |
A1 Journal article |
Year |
2015 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
Volume |
92 |
Issue |
92 |
Pages |
104104 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
The properties of a new class of phosphorene nanotubes (PNT) are investigated by performing first-principles calculations. We demonstrate that it is advantageous to use blue phosphorene in order to make small nanotubes and propose a way to create low-energy PNTs by the inclusion of defect lines. Five different types of defect lines are investigated and incorporated in various combinations. The resulting defect-induced faceted PNTs have negligible bending stresses which leads to a reduction in the formation energy with respect to round PNTs. Our armchair faceted PNTs have similar formation energies than the recently proposed multiphase faceted PNTs, but they have a larger variety of possible structures. Our zigzag faceted PNTs have lower formation energies than round tubes and multiphase faceted nanotubes. The electronic properties of the defect-induced faceted PNTs are determined by the defect lines which control the band gap and the shape of the electronic states at the band edges. These band gaps increase with the radius of the nanotubes and converge to those of isolated defect lines. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000361037200006 |
Publication Date |
2015-09-12 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
|
ISSN |
1098-0121 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
3.836 |
Times cited |
24 |
Open Access |
|
Notes |
This work was supported by the Fonds Wetenschappelijk Onderzoek (FWO-Vl). The computational resources and ser- vices used in this work were provided by the VSC (Flemish Supercomputer Center), funded by the Hercules Foundation and the Flemish Government, department EWI. |
Approved |
Most recent IF: 3.836; 2015 IF: 3.736 |
Call Number |
c:irua:127837 |
Serial |
4033 |
Permanent link to this record |
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Author |
Adami, O.-A.; Jelić, Ž.L.; Xue, C.; Abdel-Hafiez, M.; Hackens, B.; Moshchalkov, V.V.; Milošević, M.V.; Van de Vondel, J.; Silhanek, A.V. |
Title |
Onset, evolution, and magnetic braking of vortex lattice instabilities in nanostructured superconducting films |
Type |
A1 Journal article |
Year |
2015 |
Publication |
Physical review: B: condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
Volume |
92 |
Issue |
92 |
Pages |
134506 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
In 1976, Larkin and Ovchinnikov [Zh. Eksp. Teor. Fiz. 68, 1915 (1975) [Sov. Phys.–JETP 41, 960 (1976)]] predicted that vortex matter in superconductors driven by an electrical current can undergo an abrupt dynamic transition from a flux-flow regime to a more dissipative state at sufficiently high vortex velocities. Typically, this transition manifests itself as a large voltage jump at a particular current density, so-called instability current density J∗, which is smaller than the depairing current. By tuning the effective pinning strength in Al films, using an artificial periodic pinning array of triangular holes, we show that a unique and well-defined instability current density exists if the pinning is strong, whereas a series of multiple voltage transitions appear in the relatively weaker pinning regime. This behavior is consistent with time-dependent Ginzburg-Landau simulations, where the multiple-step transition can be unambiguously attributed to the progressive development of vortex chains and subsequently phase-slip lines. In addition, we explore experimentally the magnetic braking effects, caused by a thick Cu layer deposited on top of the superconductor, on the instabilities and the vortex ratchet effect. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000362433200003 |
Publication Date |
2015-10-08 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
|
ISSN |
1098-0121 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
3.836 |
Times cited |
21 |
Open Access |
|
Notes |
ACKNOWLEDGMENTS: This work was partially supported by the Fonds de la Recherche Scientifique-FNRS, the Methusalem Funding of the Flemish Government, the Research Foundation-Flanders (FWO), and COST Action MP1201. The work of A.V.S. and Z.L.J. is partially supported by “Mandat d’Impulsion Scientifique” MIS F.4527.13 of the F.R.S.-FNRS. B.H. is an associate researcher of the Fonds de la Recherche Scientifique- FNRS. The authors thank J. Cuppens for the data analysis at the early stage of this work, R. Delamare for his valuable help during the fabrication of the samples, and G. Grimaldi for helpful discussions. |
Approved |
Most recent IF: 3.836; 2015 IF: 3.736 |
Call Number |
c:irua:128747 |
Serial |
3981 |
Permanent link to this record |
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Author |
Pizzochero, M.; Leenaerts, O.; Partoens, B.; Martinazzo, R.; Peeters, F.M. |
Title |
Hydrogen adsorption on nitrogen and boron doped graphene |
Type |
A1 Journal article |
Year |
2015 |
Publication |
Journal of physics : condensed matter |
Abbreviated Journal |
J Phys-Condens Mat |
Volume |
27 |
Issue |
27 |
Pages |
425502 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
Hydrogen adsorption on boron and nitrogen doped graphene is investigated in detail by means of first-principles calculations. A comprehensive study is performed of the structural, electronic, and magnetic properties of chemisorbed hydrogen atoms and atom pairs near the dopant sites. The main effect of the substitutional atoms is charge doping which is found to greatly affect the adsorption process by increasing the binding energy at the sites closest to the substitutional species. It is also found that doping does not induce magnetism despite the odd number of electrons per atom introduced by the foreign species, and that it quenches the paramagnetic response of chemisorbed H atoms on graphene. Overall, the effects are similar for B and N doping, with only minor differences in the adsorption energetics due to different sizes of the dopant atoms and the accompanying lattice distortions. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
English |
Wos |
000362573500008 |
Publication Date |
2015-10-06 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0953-8984;1361-648X; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
2.649 |
Times cited |
20 |
Open Access |
|
Notes |
This work was supported by the Flemish Science Foundation (FWO-Vl). MP gratefully acknowledges the Condensed Matter Theory group at Universiteit Antwerpen for the hospitality during his stay. |
Approved |
Most recent IF: 2.649; 2015 IF: 2.346 |
Call Number |
c:irua:128759 |
Serial |
3971 |
Permanent link to this record |
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|
Author |
Muñoz, W.A.; Covaci, L.; Peeters, F.M. |
Title |
Disordered graphene Josephson junctions |
Type |
A1 Journal article |
Year |
2015 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
Volume |
91 |
Issue |
91 |
Pages |
054506 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
A tight-binding approach based on the Chebyshev-Bogoliubov-de Gennes method is used to describe disordered single-layer graphene Josephson junctions. Scattering by vacancies, ripples, or charged impurities is included. We compute the Josephson current and investigate the nature of multiple Andreev reflections, which induce bound states appearing as peaks in the density of states for energies below the superconducting gap. In the presence of single-atom vacancies, we observe a strong suppression of the supercurrent, which is a consequence of strong intervalley scattering. Although lattice deformations should not induce intervalley scattering, we find that the supercurrent is still suppressed, which is due to the presence of pseudomagnetic barriers. For charged impurities, we consider two cases depending on whether the average doping is zero, i.e., existence of electron-hole puddles, or finite. In both cases, short-range impurities strongly affect the supercurrent, similar to the vacancies scenario. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000349436500001 |
Publication Date |
2015-02-06 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
|
ISSN |
1098-0121;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
3.836 |
Times cited |
7 |
Open Access |
|
Notes |
This work was supported by the Flemish Science Foundation (FWO-Vlaanderen) and the Methusalem funding of the Flemish Government. |
Approved |
Most recent IF: 3.836; 2015 IF: 3.736 |
Call Number |
c:irua:129192 |
Serial |
3961 |
Permanent link to this record |
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Author |
Sobrino Fernandez, M.M.; Neek-Amal, M.; Peeters, F.M. |
Title |
AA-stacked bilayer square ice between graphene layers |
Type |
A1 Journal article |
Year |
2015 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
Volume |
92 |
Issue |
92 |
Pages |
245428 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
Water confined between two graphene layers with a separation of a few A forms a layered two-dimensional ice structure. Using large scale molecular dynamics simulations with the adoptable ReaxFF interatomic potential we found that flat monolayer ice with a rhombic-square structure nucleates between the graphene layers which is nonpolar and nonferroelectric. We provide different energetic considerations and H-bonding results that explain the interlayer and intralayer properties of two-dimensional ice. The controversial AA stacking found experimentally [Algara-Siller et al., Nature (London) 519, 443 (2015)] is consistent with our minimum-energy crystal structure of bilayer ice. Furthermore, we predict that an odd number of layers of ice has the same lattice structure as monolayer ice, while an even number of ice layers exhibits the square ice AA stacking of bilayer ice. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Lancaster, Pa |
Editor |
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Language |
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Wos |
000366731800004 |
Publication Date |
2015-12-17 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1098-0121; 1550-235x |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
3.836 |
Times cited |
40 |
Open Access |
|
Notes |
; This work was supported by the ESF-Eurographene project CONGRAN, and the Flemish Science Foundation (FWO-Vl). ; |
Approved |
Most recent IF: 3.836; 2015 IF: 3.736 |
Call Number |
c:irua:130203 |
Serial |
4127 |
Permanent link to this record |
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Author |
Dell'Anna, L.; Perali, A.; Covaci, L.; Neilson, D. |
Title |
Using magnetic stripes to stabilize superfluidity in electron-hole double monolayer graphene |
Type |
A1 Journal article |
Year |
2015 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
Volume |
92 |
Issue |
92 |
Pages |
220502 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
Experiments have confirmed that double monolayer graphene does not generate finite-temperature electron-hole superfluidity, because of very strong screening of the pairing attraction. The linear dispersing energy bands in monolayer graphene block any attempt to reduce the strength of the screening. We propose a hybrid device with two sheets of monolayer graphene in a modulated periodic perpendicular magnetic field. The field preserves the isotropic Dirac cones of the original monolayers but reduces the slope of the cones, making the monolayer Fermi velocity v(F) smaller. We demonstrate that with current experimental techniques, the reduction in vF can weaken the screening sufficiently to allow electron-hole superfluidity at measurable temperatures. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000366500100004 |
Publication Date |
2015-12-14 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1098-0121 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
3.836 |
Times cited |
7 |
Open Access |
|
Notes |
; We thank M. Zarenia for useful discussions. L.D. acknowledges financial support from MIUR: FIRB 2012, Grant No. RBFR12NLNA_002, and PRIN, Grant No. 2010LLKJBX. A.P. and D.N. acknowledge financial support from University of Camerino FAR project CESEMN. L.C. acknowledges financial support from Flemish Science Foundation (FWO). ; |
Approved |
Most recent IF: 3.836; 2015 IF: 3.736 |
Call Number |
c:irua:130211 |
Serial |
4069 |
Permanent link to this record |
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Author |
Mulkers, J.; Milošević, M.V.; Van Waeyenberge, B. |
Title |
Cycloidal versus skyrmionic states in mesoscopic chiral magnets |
Type |
A1 Journal article |
Year |
2016 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
Volume |
93 |
Issue |
93 |
Pages |
214405 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
When subjected to the interfacially induced Dzyaloshinskii-Moriya interaction, the ground state in thin ferromagnetic films with high perpendicular anisotropy is cycloidal. The period of this cycloidal state depends on the strength of the Dzyaloshinskii-Moriya interaction. In this work, we have studied the effect of confinement on the magnetic ground state and excited states, and we determined the phase diagram of thin strips and thin square platelets by means of micromagnetic calculations. We show that multiple cycloidal states with different periods can be stable in laterally confined films, where the period of the cycloids does not depend solely on the Dzyaloshinskii-Moriya interaction strength but also on the dimensions of the film. The more complex states comprising skyrmions are also found to be stable, though with higher energy. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Language |
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Wos |
000377298600006 |
Publication Date |
2016-06-06 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2469-9950 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
3.836 |
Times cited |
28 |
Open Access |
|
Notes |
; ; |
Approved |
Most recent IF: 3.836 |
Call Number |
c:irua:133919 |
Serial |
4081 |
Permanent link to this record |
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Author |
Juchtmans, R.; Béché, A.; Abakumov, A.; Batuk, M.; Verbeeck, J. |
Title |
Using electron vortex beams to determine chirality of crystals in transmission electron microscopy |
Type |
A1 Journal article |
Year |
2015 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
Volume |
91 |
Issue |
91 |
Pages |
094112 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
Abstract |
We investigate electron vortex beams elastically scattered on chiral crystals. After deriving a general expression for the scattering amplitude of a vortex electron, we study its diffraction on point scatterers arranged on a helix. We derive a relation between the handedness of the helix and the topological charge of the electron vortex on one hand and the symmetry of the higher-order Laue zones in the diffraction pattern on the other for kinematically and dynamically scattered electrons. We then extend this to atoms arranged on a helix as found in crystals which belong to chiral space groups and propose a method to determine the handedness of such crystals by looking at the symmetry of the diffraction pattern. In contrast to alternative methods, our technique does not require multiple scattering, which makes it possible to also investigate extremely thin samples in which multiple scattering is suppressed. In order to verify the model, elastic scattering simulations are performed, and an experimental demonstration on Mn2Sb2O7 is given in which we find the sample to belong to the right-handed variant of its enantiomorphic pair. This demonstrates the usefulness of electron vortex beams to reveal the chirality of crystals in a transmission electron microscope and provides the required theoretical basis for further developments in this field. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
000352017000002 |
Publication Date |
2015-03-27 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1098-0121;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
3.836 |
Times cited |
54 |
Open Access |
|
Notes |
Fwo; 312483 Esteem2; 278510 Vortex; esteem2jra1; esteem2jra2 ECASJO_; |
Approved |
Most recent IF: 3.836; 2015 IF: 3.736 |
Call Number |
c:irua:125512 c:irua:125512 |
Serial |
3825 |
Permanent link to this record |