Records |
Author |
Shakouri, K.; Szafran, B.; Esmaeilzadeh, M.; Peeters, F.M. |
Title |
Effective spin-orbit interaction Hamiltonian for quasi-one-dimensional quantum rings |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
Volume |
85 |
Issue |
16 |
Pages |
165314-165314,8 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
The effective Hamiltonian for an electron in a quasi-one-dimensional quantum ring in the presence of spin-orbit interactions is derived. We demonstrate that, when both coupling types are simultaneously present, the effective Hamiltonian derived by the lowest-radial-state approximation produces energy spectra and charge densities which deviate strongly from the exact ones. For equal Rashba and Dresselhaus coupling constants the lowest-radial-state approximation opens artifactal avoided crossings in the energy spectra and deforms the circular symmetry of the confined charge densities. In this case, there does not exist a ring thin enough to justify the restriction to the lowest radially quantized energy state. We derive the effective Hamiltonian accounting for both the lowest and the first excited radial states, and show that the inclusion of the latter restores the correct features of the exact solution. Relation of this result to the states of a quantum wire is also discussed. |
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 |
000303068800006 |
Publication Date |
2012-04-20 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
|
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 |
32 |
Open Access |
|
Notes |
; This work was partially supported by Polish Ministry of Science and Higher Education and its grants for Scientific Research. ; |
Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
Call Number |
UA @ lucian @ c:irua:98258 |
Serial |
855 |
Permanent link to this record |
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Author |
Nasr Esfahani, D.; Covaci, L.; Peeters, F.M. |
Title |
Electric-field-induced shift of the Mott metal-insulator transition in thin films |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
Volume |
85 |
Issue |
8 |
Pages |
085110-085110,8 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
The ground-state properties of a paramagnetic Mott insulator at half-filling are investigated in the presence of an external electric field using the inhomogeneous Gutzwiller approximation for a single-band Hubbard model in a slab geometry. We find that the metal-insulator transition is shifted toward higher Hubbard repulsions by applying an electric field perpendicular to the slab. The main reason is the accumulation of charges near the surface. The spatial distribution of site-dependent quasiparticle weight shows that it is maximal in a few layers beneath the surface, while the central sites where the field is screened have a very low quasiparticle weight. Our results show that above a critical-field value, states near the surface will be metallic, while the bulk quasiparticle weight is extremely suppressed but never vanishing, even for large Hubbard repulsions above the bulk zero-field critical value. Below the critical-field value, our results hint toward an insulating state in which the electric field is totally screened and the slab is again at half-filling. |
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 |
000300240100002 |
Publication Date |
2012-02-14 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
|
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 |
3 |
Open Access |
|
Notes |
; This work was supported by the Flemish Science Foundation (FWO-Vlaanderen) and the Belgian Science Policy (IAP). ; |
Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
Call Number |
UA @ lucian @ c:irua:97208 |
Serial |
884 |
Permanent link to this record |
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Author |
Avetisyan, A.A.; Partoens, B.; Peeters, F.M. |
Title |
Electric field tuning of the band gap in four layers of graphene with different stacking order |
Type |
P1 Proceeding |
Year |
2012 |
Publication |
Proceedings of the Society of Photo-optical Instrumentation Engineers
T2 – Conference on Photonics and Micro and Nano-structured Materials, JUN 28-30, 2011, Yerevan, ARMENIA |
Abbreviated Journal |
|
Volume |
|
Issue |
|
Pages |
84140-84148 |
Keywords |
P1 Proceeding; Engineering sciences. Technology; Condensed Matter Theory (CMT) |
Abstract |
We investigated the effect of different stacking order of the four graphene layer system on the induced band gap when positively charged top and negatively charged back gates are applied to the system. A tight-binding approach within a self-consistent Hartree approximation is used to calculate the induced charges on the different graphene layers. We show that the electric field does not open an energy gap if the multilayer graphene system contains a trilayer part with the ABA Bernal stacking. |
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 |
000303856600012 |
Publication Date |
2012-01-20 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
8414 |
Series Issue |
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Edition |
|
ISSN |
|
ISBN |
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Additional Links |
UA library record; WoS full record |
Impact Factor |
|
Times cited |
|
Open Access |
|
Notes |
; This work was supported by the Flemish Science Foundation (FWO-Vl), and the BelgianScience Policy (IAP). One of us (A.A.A.) was supported by a fellowship from the Belgian Federal Science Policy Office (BELSPO). ; |
Approved |
Most recent IF: NA |
Call Number |
UA @ lucian @ c:irua:113046 |
Serial |
886 |
Permanent link to this record |
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Author |
Badalyan, S.M.; Peeters, F.M. |
Title |
Electron-phonon bound state in graphene |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
Volume |
85 |
Issue |
20 |
Pages |
205453-205453,5 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
The fine structure of the Dirac energy spectrum in graphene induced by electron-optical phonon coupling is investigated in the portion of the spectrum near the phonon emission threshold. The derived new dispersion equation in the immediate neighborhood below the threshold corresponds to an electron-phonon bound state. We find that the singular vertex corrections beyond perturbation theory strongly increase the electron-phonon binding energy scale. The predicted enhancement of the effective electron-phonon coupling can be measured using angle-resolved spectroscopy. |
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 |
000304649400002 |
Publication Date |
2012-05-30 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
|
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 |
12 |
Open Access |
|
Notes |
; We thank E. Rashba for the useful discussion and acknowledge support from the Belgian Science Policy (IAP) and BELSPO. ; |
Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
Call Number |
UA @ lucian @ c:irua:98939 |
Serial |
982 |
Permanent link to this record |
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|
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Author |
Zhu, J.; Badalyan, S.M.; Peeters, F.M. |
Title |
Electron-phonon bound states in graphene in a perpendicular magnetic field |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Physical review letters |
Abbreviated Journal |
Phys Rev Lett |
Volume |
109 |
Issue |
25 |
Pages |
256602-256605 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
The spectrum of electron-phonon complexes in monolayer graphene is investigated in the presence of a perpendicular quantizing magnetic field. Despite the small electron-phonon coupling, usual perturbation theory is inapplicable for the calculation of the scattering amplitude near the threshold of optical phonon emission. Our findings, beyond perturbation theory, show that the true spectrum near the phonon-emission threshold is completely governed by new branches, corresponding to bound states of an electron and an optical phonon with a binding energy of the order of alpha omega(0), where alpha is the electron-phonon coupling and omega(0) the phonon energy. DOI: 10.1103/PhysRevLett.109.256602 |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
New York, N.Y. |
Editor |
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Language |
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Wos |
000312841700011 |
Publication Date |
2012-12-22 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
0031-9007;1079-7114; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
8.462 |
Times cited |
19 |
Open Access |
|
Notes |
; We acknowledge support from the Belgian Science Policy (BELSPO) and EU, the ESF EuroGRAPHENE project CONGRAN, and the Flemisch Science Foundation (FWO-Vl). ; |
Approved |
Most recent IF: 8.462; 2012 IF: 7.943 |
Call Number |
UA @ lucian @ c:irua:105962 |
Serial |
983 |
Permanent link to this record |
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Author |
Sena, S.H.R.; Pereira, J.M.; Farias, G.A.; Peeters, F.M.; Costa Filho, R.N. |
Title |
The electronic properties of graphene and graphene ribbons under simple shear strain |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Journal of physics : condensed matter |
Abbreviated Journal |
J Phys-Condens Mat |
Volume |
24 |
Issue |
37 |
Pages |
375301 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
A tight-binding model is used to study the energy band of graphene and graphene ribbon under simple shear strain. The ribbon consists of lines of carbon atoms in an armchair or zigzag orientation where a simple shear strain is applied in the x-direction keeping the atomic distances in the y-direction unchanged. Such modification in the lattice gives an energy band that differs in several aspects from the one without any shear and with pure shear. The changes in the spectrum depend on the line displacement of the ribbon, and also on the modified hopping parameter. It is also shown that this simple shear strain tunes the electronic properties of both graphene and graphene ribbon, opening and closing energy gaps for different displacements of the system. The modified density of states is also shown. |
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 |
000308202700011 |
Publication Date |
2012-08-14 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
0953-8984;1361-648X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
2.649 |
Times cited |
15 |
Open Access |
|
Notes |
; This work was supported by CNPq (RNCF), the National Council for the Improvement of Higher Education (CAPES), the Flemish Science Foundation (FWO-Vl), the Belgian Science Policy (IAP), and the bilateral program between Flanders and Brazil. ; |
Approved |
Most recent IF: 2.649; 2012 IF: 2.355 |
Call Number |
UA @ lucian @ c:irua:101838 |
Serial |
1000 |
Permanent link to this record |
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Author |
Masir, M.R. |
Title |
Electronic properties of graphene in inhomogeneous magnetic fields |
Type |
Doctoral thesis |
Year |
2012 |
Publication |
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Abbreviated Journal |
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Volume |
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Issue |
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Pages |
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Keywords |
Doctoral thesis; Condensed Matter Theory (CMT) |
Abstract |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Antwerpen |
Editor |
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Language |
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Wos |
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Publication Date |
0000-00-00 |
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 |
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ISBN |
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Additional Links |
UA library record |
Impact Factor |
|
Times cited |
|
Open Access |
|
Notes |
|
Approved |
Most recent IF: NA |
Call Number |
UA @ lucian @ c:irua:98178 |
Serial |
1001 |
Permanent link to this record |
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Author |
Kishore, V.V.R.; Partoens, B.; Peeters, F.M. |
Title |
Electronic structure of InAs/GaSb core-shell nanowires |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
Volume |
86 |
Issue |
16 |
Pages |
165439-7 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
The electronic and optical properties of InAs/GaSb core-shell nanowires are investigated within the effective mass k . p approach. These systems have a broken band gap, which results in spatially separated confinement of electrons and holes. We investigated these structures for different sizes of the InAs and GaSb core and shell radius. We found that for certain configurations, the conduction band states penetrate into the valence band states resulting in a negative band gap (E-g < 0), which leads to a conduction band ground state that lies below the valence band ground state at the Gamma point. For certain core-shell wires, only one conduction band state penetrates into the valence band and in this case, a minigap Delta opens up away from the Gamma point and as a consequence the electronic properties of the nanowire now depend on both E-g and Delta values. |
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 |
000310131400005 |
Publication Date |
2012-10-23 |
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 |
|
ISSN |
1098-0121;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
3.836 |
Times cited |
26 |
Open Access |
|
Notes |
; This work was supported by the Flemish Science Foundation (FWO-Vl). ; |
Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
Call Number |
UA @ lucian @ c:irua:102164 |
Serial |
1014 |
Permanent link to this record |
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Author |
Dixit, H.; Saniz, R.; Cottenier, S.; Lamoen, D.; Partoens, B. |
Title |
Electronic structure of transparent oxides with the Tran-Blaha modified Becke-Johnson potential |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Journal of physics : condensed matter |
Abbreviated Journal |
J Phys-Condens Mat |
Volume |
24 |
Issue |
20 |
Pages |
205503-205503,9 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT) |
Abstract |
We present electronic band structures of transparent oxides calculated using the Tran-Blaha modified Becke-Johnson (TB-mBJ) potential. We studied the basic n-type conducting binary oxides In2O3, ZnO, CdO and SnO2 along with the p-type conducting ternary oxides delafossite CuXO2 (X = Al, Ga, In) and spinel ZnX2O4 (X = Co, Rh, Ir). The results are presented for calculated band gaps and effective electron masses. We discuss the improvements in the band gap determination using TB-mBJ compared to the standard generalized gradient approximation (GGA) in density functional theory (DFT) and also compare the electronic band structure with available results from the quasiparticle GW method. It is shown that the calculated band gaps compare well with the experimental and GW results, although the electron effective mass is generally overestimated. |
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 |
000303507100009 |
Publication Date |
2012-04-27 |
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 |
|
ISSN |
0953-8984;1361-648X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
2.649 |
Times cited |
113 |
Open Access |
|
Notes |
Iwt; Fwo |
Approved |
Most recent IF: 2.649; 2012 IF: 2.355 |
Call Number |
UA @ lucian @ c:irua:98222 |
Serial |
1017 |
Permanent link to this record |
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Author |
Krstajić, P.M.; Peeters, F.M. |
Title |
Energy-momentum dispersion relation of plasmarons in graphene |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
Volume |
85 |
Issue |
20 |
Pages |
205454-205454,4 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
The many-body correction to the band structure of a quasi-free-standing graphene layer is obtained within the Overhauser approach, where the electron-plasmon interaction is described as a field theoretical problem. We find that the Dirac-like spectrum is shifted by Delta E(k = 0), which is on the order of 50-150 meV, depending on the electron concentration n(e), and is in semiquantitative agreement with experimental data. The value of the Fermi velocity is renormalized by several percents and decreases with increasing electron concentration as found experimentally. |
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 |
000304649900004 |
Publication Date |
2012-06-05 |
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 |
11 |
Open Access |
|
Notes |
; This work was supported by the Flemish Science Foundation (FWO-Vl), the ESF-EuroGRAPHENE project CON-GRAN, and the Serbian Ministry of Education and Science (project No. TR 32008). ; |
Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
Call Number |
UA @ lucian @ c:irua:98937 |
Serial |
1043 |
Permanent link to this record |
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Author |
Badalyan, S.M.; Peeters, F.M. |
Title |
Enhancement of Coulomb drag in double-layer graphene structures by plasmons and dielectric background inhomogeneity |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
Volume |
86 |
Issue |
12 |
Pages |
121405 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
The drag of massless fermions in graphene double-layer structures is investigated over a wide range of temperatures and interlayer separations. We show that the inhomogeneity of the dielectric background in such graphene structures, for experimentally relevant parameters, results in a significant enhancement of the drag resistivity. At intermediate temperatures the dynamical screening via plasmon-mediated drag enhances the drag resistivity and results in an upturn in its behavior at large interlayer separations. In a range of interlayer separations, corresponding to the crossover from strong to weak coupling of graphene layers, we find that the decrease of the drag resistivity with interlayer spacing is approximately quadratic. This dependence weakens below this range of interlayer spacing while for larger separations we find a cubic (quartic) dependence at intermediate (low) temperatures. |
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 |
000309178100003 |
Publication Date |
2012-09-21 |
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 |
; We acknowledge support from the Flemisch Science Foundation (FWO-Vl) and the Belgian Science Policy (BELSPO). ; |
Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
Call Number |
UA @ lucian @ c:irua:101834 |
Serial |
1060 |
Permanent link to this record |
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Author |
Vodolazov, D.Y.; Peeters, F.M. |
Title |
Enhancement of the retrapping current of superconducting microbridges of finite length |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
Volume |
85 |
Issue |
2 |
Pages |
024508-024508,6 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
We theoretically find that the resistance of a superconducting microbridge or nanowire decreases while the retrapping current I(r) for the transition to the superconducting state increases when one suppresses the magnitude of the order parameter vertical bar Delta vertical bar in the attached superconducting leads. This effect is a consequence of the increased energy interval for diffusion of the “hot” nonequilibrium quasiparticles (induced by the oscillations of vertical bar Delta vertical bar in the center of the microbridge) to the leads. The effect is absent in short microbridges (with length less than the coherence length) and it is relatively weak in long microbridges (with length larger than the inelastic relaxation length of the nonequilibrium distribution function). A nonmonotonous dependence of I(r) on the length of the microbridge is predicted. Our results are important for the explanation of the enhancement of the critical current and the appearance of negative magnetoresistance observed in many recent experiments on superconducting microbridges or nanowires. |
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 |
000298863400005 |
Publication Date |
2012-01-06 |
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 |
|
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 Russian Foundation for Basic Research, Russian Agency of Education, under the Federal Target Programme “Scientific and Educational Personnel of Innovative Russia in 2009-2013” and the Flemish Science Foundation (FWO-Vl). ; |
Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
Call Number |
UA @ lucian @ c:irua:96235 |
Serial |
1065 |
Permanent link to this record |
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Author |
Arsoski, V.; Čukarić, N.; Tadić, M.; Peeters, F.M. |
Title |
Exciton states in a nanocup in the presence of a perpendicular magnetic field |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Physica scripta |
Abbreviated Journal |
Phys Scripta |
Volume |
T149 |
Issue |
|
Pages |
014054-014054,5 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
The exciton states in a strained (In,Ga)As/GaAs nanocup are theoretically determined. We explore how the nanocup bottom thickness (t) affects the magnetic field dependence of the exciton energy. Strain distribution is computed by the continuum mechanical model under the approximation of isotropic elasticity. The exciton wave functions are expanded into products of the electron and hole envelope functions. For small t, the exciton ground state has zero orbital momentum and exhibits small oscillations of the second derivative when the magnetic field increases. When t approaches the value of the cup height, however, the exciton levels exhibit angular momentum transitions, whose behavior is similar to that for type-II quantum dots. Small oscillations of the oscillator strength for exciton recombination are found when the magnetic field increases. An increase in thickness of the nanocup bottom has only a small effect on those oscillations for the optically active exciton states, but the exciton ground state becomes dark when the magnetic field increases. Hence, the results of our calculations show that an increase in thickness of the nanocup bottom transforms the exciton ground energy level dependence on magnetic field from the one characteristic of type-I rings to the one characteristic of type-II dots. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Stockholm |
Editor |
|
Language |
|
Wos |
000303523500055 |
Publication Date |
2012-04-27 |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
0031-8949;1402-4896; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
1.28 |
Times cited |
2 |
Open Access |
|
Notes |
; This work was supported by the EU Network of Excellence SANDiE, the Ministry of Education and Science of Serbia, the Flemish Science Foundation (FWO-Vl) and the Belgian Science Policy (IAP). ; |
Approved |
Most recent IF: 1.28; 2012 IF: 1.032 |
Call Number |
UA @ lucian @ c:irua:99135 |
Serial |
1117 |
Permanent link to this record |
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Author |
Vagov, A.V.; Shanenko, A.A.; Milošević, M.V.; Axt, V.M.; Peeters, F.M. |
Title |
Extended Ginzburg-Landau formalism : systematic expansion in small deviation from the critical temperature |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
Volume |
85 |
Issue |
1 |
Pages |
014502-014502,17 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
Based on the Gor'kov formalism for a clean s-wave superconductor, we develop an extended version of the single-band Ginzburg-Landau (GL) theory by means of a systematic expansion in the deviation from the critical temperature T(c), i.e., tau = 1 – T/T(c). We calculate different contributions to the order parameter and the magnetic field: the leading contributions (proportional to tau(1/2) in the order parameter and. t in the magnetic field) are controlled by the standard GL theory, while the next-to-leading terms (proportional to tau(3/2) in the gap and proportional to tau(2) in the magnetic field) constitute the extended GL (EGL) approach. We derive the free-energy functional for the extended formalism and the corresponding expression for the current density. To illustrate the usefulness of our formalism, we calculate, in a semianalytical form, the temperature-dependent correction to the GL parameter at which the surface energy becomes zero, and analytically, the temperature dependence of the thermodynamic critical field. We demonstrate that the EGL formalism is not just a mathematical extension to the theory: variations of both the gap and the thermodynamic critical field with temperature calculated within the EGL theory are found in very good agreement with the full BCS results down to low temperatures, which dramatically improves the applicability of the formalism compared to its standard predecessor. |
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 |
000298985100002 |
Publication Date |
2012-01-10 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
|
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 |
36 |
Open Access |
|
Notes |
; This work was supported by the Flemish Science Foundation (FWO-Vl) and the Belgian Science Policy (IAP). A. V. V. is grateful to V. Zalipaev for important comments. A. A. S. thanks W. Pogosov for helpful notes. Discussions with E. H. Brandt and A. Perali are appreciated. ; |
Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
Call Number |
UA @ lucian @ c:irua:96232 |
Serial |
1155 |
Permanent link to this record |
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|
|
Author |
Dixit, H. |
Title |
First-principles electronic structure calculations of transparent conducting oxide materials |
Type |
Doctoral thesis |
Year |
2012 |
Publication |
|
Abbreviated Journal |
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Volume |
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Issue |
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Pages |
|
Keywords |
Doctoral thesis; Condensed Matter Theory (CMT) |
Abstract |
|
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Antwerpen |
Editor |
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Language |
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Wos |
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Publication Date |
0000-00-00 |
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 |
|
ISBN |
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Additional Links |
UA library record |
Impact Factor |
|
Times cited |
|
Open Access |
|
Notes |
|
Approved |
Most recent IF: NA |
Call Number |
UA @ lucian @ c:irua:99490 |
Serial |
1209 |
Permanent link to this record |
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|
Author |
Sivek, J.; Leenaerts, O.; Partoens, B.; Peeters, F.M. |
Title |
First-principles investigation of bilayer fluorographene |
Type |
A1 Journal article |
Year |
2012 |
Publication |
The journal of physical chemistry: C : nanomaterials and interfaces |
Abbreviated Journal |
J Phys Chem C |
Volume |
116 |
Issue |
36 |
Pages |
19240-19245 |
Keywords |
A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT) |
Abstract |
Ab initio calculations within the density functional theory formalism are performed to investigate the stability and electronic properties of fluorinated bilayer graphene (bilayer fluorographene). A comparison is made to previously investigated graphane, bilayer graphane, and fluorographene. Bilayer fluorographene is found to be a much more stable material than bilayer graphane. Its electronic band structure is similar to that of monolayer fluorographene, but its electronic band gap is significantly larger (about 1 eV). We also calculate the effective masses around the Gamma-point for fluorographene and bilayer fluorographene and find that they are isotropic, in contrast to earlier reports. Furthermore, it is found that bilayer fluorographene is almost as strong as graphene, as its 2D Young's modulus is approximately 300 N m(-1). |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Washington, D.C. |
Editor |
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Language |
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Wos |
000308631300022 |
Publication Date |
2012-08-21 |
Series Editor |
|
Series Title |
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Abbreviated Series Title |
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Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
1932-7447;1932-7455; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
4.536 |
Times cited |
39 |
Open Access |
|
Notes |
; This work is supported by the ESF-Eurocores program EuroGRAPHENE (project CONERAN) and the Flemish Science Foundation (FWO-V1). ; |
Approved |
Most recent IF: 4.536; 2012 IF: 4.814 |
Call Number |
UA @ lucian @ c:irua:101842 |
Serial |
1211 |
Permanent link to this record |
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Author |
Berdiyorov, G.R.; Hernández-Nieves, A.D.; Milošević, M.V.; Peeters, F.M.; Dominguez, D. |
Title |
Flux-quantum-discretized dynamics of magnetic flux entry, exit, and annihilation in current-driven mesoscopic type-I superconductors |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
Volume |
85 |
Issue |
9 |
Pages |
092502-092502,4 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
We study nonlinear flux dynamics in a current-carrying type-I superconductor. The stray magnetic field of the current induces the intermediate state, where nucleation of flux domains is discretized to a single fluxoid at a time, while their final shape (tubular or laminar), size, and nucleation rate depend on applied current and edge conditions. The current induces opposite flux domains on opposite sides of the sample, and subsequently drives them to annihilation-which is also discretized, as a sequence of vortex-antivortex pairs. The discretization of both nucleation and annihilation leaves measurable traces in the voltage across the sample and in locally probed magnetization. The reported dynamic phenomena thus provide an unambiguous proof of a flux quantum being the smallest building block of the intermediate state in type-I superconductors. |
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 |
000301183000002 |
Publication Date |
2012-03-07 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
|
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 |
14 |
Open Access |
|
Notes |
; This work was supported by the Belgian Science Policy (IAP), the Flemish Science Foundation (FWO-Vl), and the collaborative project FWO-MINCyT (Project No. FW/08/01). G. R. B. and A. D. H acknowledge support from FWO-Vl. A. D. H. and D. D. acknowledge support from CONICET, CNEA, and ANPCyT (Grant No. PICT07-824). ; |
Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
Call Number |
UA @ lucian @ c:irua:97180 |
Serial |
1243 |
Permanent link to this record |
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|
Author |
Peelaers, H.; Partoens, B.; Peeters, F.M. |
Title |
Free-standing Si and Ge, and Ge/Si core-shell semiconductor nanowires |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Acta physica Polonica: A: general physics, solid state physics, applied physics
T2 – WELCOME Scientific Meeting on Hybrid Nanostructures, AUG 28-31, 2011, Torun, POLAND |
Abbreviated Journal |
Acta Phys Pol A |
Volume |
122 |
Issue |
2 |
Pages |
294-298 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
The properties of free-standing silicon and germanium nanowires oriented along the [110] direction are studied using different first principles methods. We show the corrections due to quasi-particles to the band structures obtained using the local-density approximation. The formation energies of B and P doped nanowires are calculated, both in the absence and presence of dangling bond defects and we link these to experimental results. Furthermore, we report on the phonon properties of pure Si and Ge nanowires, as well as Ge/Si core-shell nanowires, and discuss the differences between them. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Warszawa |
Editor |
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Language |
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Wos |
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Publication Date |
0000-00-00 |
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 |
0587-4246 |
ISBN |
|
Additional Links |
UA library record; WoS full record; |
Impact Factor |
0.469 |
Times cited |
|
Open Access |
|
Notes |
|
Approved |
Most recent IF: 0.469; 2012 IF: 0.531 |
Call Number |
UA @ lucian @ c:irua:101896 |
Serial |
1277 |
Permanent link to this record |
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Author |
Saniz, R.; Partoens, B.; Peeters, F.M. |
Title |
Green function approach to superconductivity in nanowires |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
Volume |
85 |
Issue |
14 |
Pages |
144504-144504,7 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
Superconductivity in nanowires made of weak coupling superconductor materials is investigated using a Green function approach. We show that these are multigap systems in which the ratio Delta(T)/k(B)T(c) is to a large extent similar to what is observed in some high-T-c two-gap systems, such as MgB2 and some of the Fe-based superconductors. On the other hand, because of confinement, the superfluid density has a temperature behavior of the form n(s)(T) = 1 – (T/T-c)(3) near T-c, thus deviating from the BCS behavior for bulk superconductors. |
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 |
000302290700006 |
Publication Date |
2012-04-03 |
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 |
1 |
Open Access |
|
Notes |
; This work was supported by FWO-Vl and the Belgian Science Policy (IAP). ; |
Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
Call Number |
UA @ lucian @ c:irua:97764 |
Serial |
1381 |
Permanent link to this record |
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Author |
Čukarić, N.; Arsoski, V.; Tadić, M.; Peeters, F.M. |
Title |
Hole states in nanocups in a magnetic field |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
Volume |
85 |
Issue |
23 |
Pages |
235425-235425,11 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
The magnetic-field dependence of the hole states in a nanocup, which is composed of a ring (the nanocup rim) that surrounds a disk (the nanocup bottom), is obtained within the Luttinger-Kohn model for the unstrained GaAs/(Al,Ga) As and the strained (In,Ga) As/GaAs systems. Aharonov-Bohm oscillations due to angular momentum transitions of the hole ground state appear with periods that vary with the thickness of the disk. The strain in the (In, Ga) As/GaAs nanocup is sensitive to the disk thickness and favors the spatial localization of the heavy holes inside the disk. Therefore, the angular momentum transitions between the valence-band states disappear for much thinner disks than in the case of the unstrained GaAs/(Al, Ga) As nanocups. In both systems, the oscillations in the energy of the hole ground state are found to disappear for thinner inner layer than in the electron ground-state energy. This is due to the different confining potentials and the mixing between the heavy- and light-hole states. As a consequence, magnetization of the single hole is found to strongly depend on the bottom thickness of the strained (In, Ga) As/GaAs nanocup. Furthermore, we found that the strain can lead to a spatial separation of the electron and the hole, as in type-II band alignment, which is advantageous for the appearance of the excitonic Aharonov-Bohm 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 |
000305116700005 |
Publication Date |
2012-06-14 |
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;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
3.836 |
Times cited |
4 |
Open Access |
|
Notes |
; The authors thank B. Partoens for useful discussions. This work was supported by the EU NoE: SANDiE, the Ministry of Education and Science of Serbia, and the Belgian Science Policy (IAP). ; |
Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
Call Number |
UA @ lucian @ c:irua:98906 |
Serial |
1477 |
Permanent link to this record |
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Author |
Kishore, V.V.R.; Čukarić, N.; Partoens, B.; Tadić, M.; Peeters, F.M. |
Title |
Hole subbands in freestanding nanowires : six-band versus eight-band k.p modelling |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Journal of physics : condensed matter |
Abbreviated Journal |
J Phys-Condens Mat |
Volume |
24 |
Issue |
13 |
Pages |
135302-135302,10 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
The electronic structure of GaAs, InAs and InSb nanowires is studied using the six-band and the eight-band k.p models. The effect of the different Luttinger-like parameters (in the eight-band model) on the hole band structure is investigated. Although GaAs nanostructures are often treated within a six-band model because of the large bandgap, it is shown that an eight-band model is necessary for a correct description of its hole spectrum. The camel-back structure usually found in the six-band model is not always present in the eight-band model. This camel-back structure depends on the interaction between light and heavy holes, especially the ones with opposite spin. The latter effect is less pronounced in an eight-band model, but could be very sensitive to the Kane inter-band energy (E-P) value. |
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 |
000302120100007 |
Publication Date |
2012-03-06 |
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 |
13 |
Open Access |
|
Notes |
; This work was supported by the Flemish Science Foundation (FWO-Vl), Belgian Science Policy (IAP) and the Ministry of Education and Science of Serbia. ; |
Approved |
Most recent IF: 2.649; 2012 IF: 2.355 |
Call Number |
UA @ lucian @ c:irua:97763 |
Serial |
1479 |
Permanent link to this record |
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Author |
Li, Z.; Covaci, L.; Marsiglio, F. |
Title |
Impact of Dresselhaus versus Rashba spin-orbit coupling on the Holstein polaron |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
Volume |
85 |
Issue |
20 |
Pages |
205112-205112,5 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
We utilize an exact variational numerical procedure to calculate the ground-state properties of a polaron in the presence of Rashba and linear Dresselhaus spin-orbit coupling. We find that when the linear Dresselhaus spin-orbit coupling approaches the Rashba spin-orbit coupling, the Van Hove singularity in the density of states will be shifted away from the bottom of the band and finally disappear when the two spin-orbit couplings are tuned to be equal. The effective mass will be suppressed; the trend will become more significant for low phonon frequency. The presence of two dominant spin-orbit couplings will make it possible to tune the effective mass with more varied observables. |
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 |
000303794900003 |
Publication Date |
2012-05-09 |
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 |
1098-0121;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
3.836 |
Times cited |
18 |
Open Access |
|
Notes |
; This work was supported in part by the Natural Sciences and Engineering Research Council of Canada (NSERC), by ICORE (Alberta), by the Flemish Science Foundation (FWO-Vl), and by the Canadian Institute for Advanced Research (CIfAR). ; |
Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
Call Number |
UA @ lucian @ c:irua:99121 |
Serial |
1558 |
Permanent link to this record |
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Author |
Beheshtian, J.; Sadeghi, A.; Neek-Amal, M.; Michel, K.H.; Peeters, F.M. |
Title |
Induced polarization and electronic properties of carbon-doped boron nitride nanoribbons |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
Volume |
86 |
Issue |
19 |
Pages |
195433-195438 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
The electronic properties of boron nitride nanoribbons (BNNRs) doped with a line of carbon atoms are investigated using density functional calculations. By replacing a line of alternating B and N atoms with carbons, three different configurations are possible depending on the type of the atoms which bond to the carbons. We found very different electronic properties for these configurations: (i) the NCB arrangement is strongly polarized with a large dipole moment having an unexpected direction, (ii) the BCB and NCN arrangements are nonpolar with zero dipole moment, (iii) the doping by a carbon line reduces the band gap regardless of the local arrangement of the borons and the nitrogens around the carbon line, and (iv) the polarization and energy gap of the carbon-doped BNNRs can be tuned by an electric field applied parallel to the carbon line. Similar effects were found when either an armchair or zigzag line of carbon was introduced. |
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 |
000311694200006 |
Publication Date |
2012-11-29 |
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;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
3.836 |
Times cited |
41 |
Open Access |
|
Notes |
; We would like to thank J. M. Pereira and S. Goedecker for helpful discussions. This work was supported by the Flemish Science Foundation (FWO-Vl), the ESF-EuroGRAPHENE project CONGRAN. M. N.-A is supported by EU-Marie Curie IIF postdoc Fellowship/299522. ; |
Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
Call Number |
UA @ lucian @ c:irua:105136 |
Serial |
1603 |
Permanent link to this record |
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Author |
Sarmadian, N.; Saniz, R.; Lamoen, D.; Partoens, B. |
Title |
Influence of Al concentration on the optoelectronic properties of Al-doped MgO |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
Volume |
86 |
Issue |
20 |
Pages |
205129-5 |
Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT) |
Abstract |
We use density functional theory within the local density approximation to investigate the structural, electronic, and optical properties of Al-doped MgO. The concentrations considered range from 6% to 56%. In the latter case, we also compare the optical properties of the amorphous and crystalline phases. We find that, overall, the electronic properties of the crystalline phases change qualitatively little with Al concentration. On the other hand, the changes in the electronic structure in the amorphous phase are more important, most notably because of deep impurity levels in the band gap that are absent in the crystalline phase. This leads to observable effects in, e.g., the optical absorption edge and in the refractive index. Thus, the latter can be used to characterize the crystalline to amorphous transition with Al doping level. |
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 |
000311605000003 |
Publication Date |
2012-11-28 |
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 |
5 |
Open Access |
|
Notes |
Iwt; Fwo |
Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
Call Number |
UA @ lucian @ c:irua:105137 |
Serial |
1612 |
Permanent link to this record |
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Author |
Silhanek, A.V.; Leo, A.; Grimaldi, G.; Berdiyorov, G.R.; Milošević, M.V.; Nigro, A.; Pace, S.; Verellen, N.; Gillijns, W.; Metlushko, V.; Ilić, B.; Zhu, X.; Moshchalkov, V.V.; |
Title |
Influence of artificial pinning on vortex lattice instability in superconducting films |
Type |
A1 Journal article |
Year |
2012 |
Publication |
New journal of physics |
Abbreviated Journal |
New J Phys |
Volume |
14 |
Issue |
|
Pages |
053006-053006,11 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
In superconducting films under an applied dc current, we analyze experimentally and theoretically the influence of engineered pinning on the vortex velocity at which the flux-flow dissipation undergoes an abrupt transition from low to high resistance. We argue, based on a nonuniform distribution of vortex velocity in the sample, that in strongly disordered systems the mean critical vortex velocity for flux-flow instability (i) has a nonmonotonic dependence on magnetic field and (ii) decreases as the pinning strength is increased. These findings challenge the generally accepted microscopic model of Larkin and Ovchinnikov (1979 J. Low. Temp. Phys. 34 409) and all subsequent refinements of this model which ignore the presence of pinning centers. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Bristol |
Editor |
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Language |
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Wos |
000304871700003 |
Publication Date |
2012-05-04 |
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 |
1367-2630; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
3.786 |
Times cited |
40 |
Open Access |
|
Notes |
; This work was supported by the Methusalem Funding of the Flemish Government, the ESF-NES program, the Belgian Science Policy (IAP) and the Fund for Scientific Research-Flanders (FWO-Vlaanderen). AVS, GRB and WG received individual support from FWO-Vlaanderen. GG acknowledges support from the research project L.R. N5 of Regione Campania. VM acknowledges financial support from the US NSF, grant no. ECCS-0823813. We acknowledge J Van de Vondel for a critical reading of the manuscript. ; |
Approved |
Most recent IF: 3.786; 2012 IF: 4.063 |
Call Number |
UA @ lucian @ c:irua:98949 |
Serial |
1616 |
Permanent link to this record |
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Author |
Varykhalov, A.; Marchenko, D.; Sanchez-Barriga, J.; Scholz, M.R.; Verberck, B.; Trauzettel, B.; Wehling, T.O.; Carbone, C.; Rader, O. |
Title |
Intact dirac cones at broken sublattice symmetry : photoemission study of graphene on Ni and Co |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Physical review X |
Abbreviated Journal |
Phys Rev X |
Volume |
2 |
Issue |
4 |
Pages |
041017-10 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
The appearance of massless Dirac fermions in graphene requires two equivalent carbon sublattices of trigonal shape. While the generation of an effective mass and a band gap at the Dirac point remains an unresolved problem for freestanding extended graphene, it is well established by breaking translational symmetry by confinement and by breaking sublattice symmetry by interaction with a substrate. One of the strongest sublattice-symmetry-breaking interactions with predicted and measured band gaps ranging from 400 meV to more than 3 eV has been attributed to the interfaces of graphene with Ni and Co, which are also promising spin-filter interfaces. Here, we apply angle-resolved photoemission to epitaxial graphene on Ni (111) and Co(0001) to show the presence of intact Dirac cones 2.8 eV below the Fermi level. Our results challenge the common belief that the breaking of sublattice symmetry by a substrate and the opening of the band gap at the Dirac energy are in a straightforward relation. A simple effective model of a biased bilayer structure composed of graphene and a sublattice-symmetry-broken layer, corroborated by density-functional-theory calculations, demonstrates the general validity of our conclusions. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
College Park, Md |
Editor |
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Language |
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Wos |
000312703200001 |
Publication Date |
2012-12-22 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
2160-3308; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
12.789 |
Times cited |
86 |
Open Access |
|
Notes |
; A. V. acknowledges helpful discussions with N. Sandler. This work was supported by SPP 1459 of the Deutsche Forschungsgemeinschaft. B. V. acknowledges support from the Research Foundation Flanders (FWO-Vlaanderen). B. T. and T. O. W. would like to thank the KITP at Santa Barbara for hospitality during the completion of this work. ; |
Approved |
Most recent IF: 12.789; 2012 IF: 6.711 |
Call Number |
UA @ lucian @ c:irua:105964 |
Serial |
1677 |
Permanent link to this record |
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|
|
Author |
Grujić, M.; Zarenia, M.; Tadić, M.; Peeters, F.M. |
Title |
Interband optical absorption in a circular graphene quantum dot |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Physica scripta |
Abbreviated Journal |
Phys Scripta |
Volume |
T149 |
Issue |
|
Pages |
014056-014056,4 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
We investigate the energy levels and optical properties of a circular graphene quantum dot in the presence of an external magnetic field perpendicular to the dot. Based on the Dirac-Weyl equation and assuming zero outward current at the edge of the dot we present the results for two different types of boundary conditions, i.e. infinite-mass (IMBC) and zigzag boundary conditions. We found that the dot with zigzag edges displays a zero-energy state in the energy spectra while this is not the case for the IMBCs. For both boundary conditions, the confinement becomes dominated by the magnetic field, where the energy levels converge to the Landau levels as the magnetic field increases. The effect of boundary conditions on the electron-and hole-energy states is found to affect the interband absorption spectra, where we found larger absorption in the case of IMBCs. The selection rules for interband optical transitions are determined and discussed for both boundary conditions. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Stockholm |
Editor |
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Language |
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Wos |
000303523500057 |
Publication Date |
2012-04-27 |
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 |
0031-8949;1402-4896; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
1.28 |
Times cited |
5 |
Open Access |
|
Notes |
; This work was supported by the EuroGraphene program of the ESF (project CONGRAN), the Ministry of Education and Science of Serbia, the Belgian Science Policy (IAP) and the Flemish Science Foundation (FWO-Vl). ; |
Approved |
Most recent IF: 1.28; 2012 IF: 1.032 |
Call Number |
UA @ lucian @ c:irua:99136 |
Serial |
1688 |
Permanent link to this record |
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Author |
Berdiyorov, G.R.; Milošević, M.V.; Latimer, M.L.; Xiao, Z.L.; Kwok, W.K.; Peeters, F.M. |
Title |
Large magnetoresistance oscillations in mesoscopic superconductors due to current-excited moving vortices |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Physical review letters |
Abbreviated Journal |
Phys Rev Lett |
Volume |
109 |
Issue |
5 |
Pages |
057004 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
We show in the case of a superconducting Nb ladder that a mesoscopic superconductor typically exhibits magnetoresistance oscillations whose amplitude and temperature dependence are different from those stemming from the Little-Parks effect. We demonstrate that these large resistance oscillations (as well as the monotonic background on which they are superimposed) are due to current-excited moving vortices, where the applied current in competition with the oscillating Meissner currents imposes or removes the barriers for vortex motion in an increasing magnetic field. Because of the ever present current in transport measurements, this effect should be considered in parallel with the Little-Parks effect in low-critical temperature (T-c) samples, as well as with recently proposed thermal activation of dissipative vortex-antivortex pairs in high-T-c samples. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
New York, N.Y. |
Editor |
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Language |
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Wos |
000306994900024 |
Publication Date |
2012-07-31 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
0031-9007;1079-7114; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
8.462 |
Times cited |
65 |
Open Access |
|
Notes |
; This work was supported by the Flemish Science Foundation (FWO-Vl) and the Belgian Science Policy (IAP) (theory) and by the U. S. Department of Energy (DOE) Award No. DE-FG02-06ER46334 (experiment). G. R. B. acknowledges individual grant from FWO-Vl. W. K. K. acknowledges support from DOE BES under Contract No. DE-AC02-06CH11357, which also funds Argonne's Center for Nanoscale Materials (CNM) where the focused-ion-beam milling was performed. ; |
Approved |
Most recent IF: 8.462; 2012 IF: 7.943 |
Call Number |
UA @ lucian @ c:irua:100832 |
Serial |
1780 |
Permanent link to this record |
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|
Author |
Misko, V.R.; Nori, F. |
Title |
Magnetic flux pinning in superconductors with hyperbolic-tesselation arrays of pinning sites |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
Volume |
85 |
Issue |
18 |
Pages |
184506-184506,6 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
We study magnetic flux interacting with arrays of pinning sites (APSs) placed on vertices of hyperbolic tesselations (HTs). We show that, due to the gradient in the density of pinning sites, HT APSs are capable of trapping vortices for a broad range of applied magnetic fluxes. Thus, the penetration of magnetic field in HT APSs is essentially different from the usual scenario predicted by the Bean model. We demonstrate that, due to the enhanced asymmetry of the surface barrier for vortex entry and exit, this HT APS could be used as a “capacitor” to store magnetic flux. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
|
Editor |
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Language |
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Wos |
000303653600005 |
Publication Date |
2012-05-04 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
|
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 |
24 |
Open Access |
|
Notes |
; V.R.M. acknowledges support from the “Odysseus” Program of the Flemish Government & FWO-Vl, and the IAP. F.N. is partially supported by the ARO, NSF Grant No. 0726909, JSPS-RFBR Contract No. 12-02-92100, Grant-in-Aid for Scientific Research (S), MEXT Kakenhi on Quantum Cybernetics, and the JSPS via its FIRST program. ; |
Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
Call Number |
UA @ lucian @ c:irua:98224 |
Serial |
1880 |
Permanent link to this record |
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Author |
Müller, A.; Milošević, M.V.; Dale, S.E.C.; Engbarth, M.A.; Bending, S.J. |
Title |
Magnetization measurements and Ginzburg-Landau simulations of micron-size \beta-tin samples : evidence for an unusual critical behavior of mesoscopic type-I superconductors |
Type |
A1 Journal article |
Year |
2012 |
Publication |
Physical review letters |
Abbreviated Journal |
Phys Rev Lett |
Volume |
109 |
Issue |
19 |
Pages |
197003 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
We describe investigations of the largely unexplored field of mesoscopic type-I superconductors. Micromagnetometry and 3D Ginzburg-Landau simulations of our single crystal β-tin samples in this regime reveal size- and temperature-dependent supercritical fields whose behavior is radically different from the bulk critical field HcB. We find that complete suppression of the intermediate state in medium-size samples can result in a surprising reduction of the critical field significantly below HcB. We also reveal an evolution of the superconducting-to-normal phase transition from the expected irreversible first order at low temperatures through the previously unobserved reversible first-order to a second-order transition close to Tc, where the critical field can be many times larger than HcB. Finally, we have identified striking correlations between the mesoscopic Hc3 for nucleation of surface superconductivity and the thermodynamic Hc near Tc. All these observations are entirely unexpected in the conventional type-I picture. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
New York, N.Y. |
Editor |
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Language |
|
Wos |
000310853100017 |
Publication Date |
2012-11-09 |
Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
|
Series Issue |
|
Edition |
|
ISSN |
0031-9007;1079-7114; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
8.462 |
Times cited |
21 |
Open Access |
|
Notes |
; This work was supported by the EPSRC-UK under Grant No. EP/E039944/1, and the Flemish Science Foundation (FWO). ; |
Approved |
Most recent IF: 8.462; 2012 IF: 7.943 |
Call Number |
UA @ lucian @ c:irua:102401 |
Serial |
1893 |
Permanent link to this record |