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Author Bafekry, A.; Neek-Amal, M.; Peeters, F.M.
Title Two-dimensional graphitic carbon nitrides: strain-tunable ferromagnetic ordering Type A1 Journal article
Year 2020 Publication Physical Review B Abbreviated Journal Phys Rev B
Volume 101 Issue 16 Pages 165407-165408
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Using first-principle calculations, we systematically study strain tuning of the electronic properties of two- dimensional graphitic carbon nitride nanosheets with empirical formula CnNm. We found the following: (i) the ferromagnetic ordered state in the metal-free systems (n, m) = (4,3), (10,9), and (14,12) remains stable in the presence of strain of about 6%. However, the system (9,7) loses its ferromagnetic ordering when increasing strain. This is due to the presence of topological defects in the (9,7) system, which eliminates the asymmetry between spin up and spin down of the p(z) orbitals when strain is applied. (ii) By applying uniaxial strain, a band gap opens in systems which are initially gapless. (iii) In semiconducting systems which have an initial gap of about 1 eV, the band gap is closed with applying uniaxial strain.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000523630200012 Publication Date 2020-04-06
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9969; 2469-9950 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.7 Times cited 22 Open Access
Notes ; ; Approved (up) Most recent IF: 3.7; 2020 IF: 3.836
Call Number UA @ admin @ c:irua:168560 Serial 6643
Permanent link to this record
 
 
Author Milovanović, S.P.; Andelkovic, M.; Covaci, L.; Peeters, F.M.
Title Band flattening in buckled monolayer graphene Type A1 Journal article
Year 2020 Publication Physical Review B Abbreviated Journal Phys Rev B
Volume 102 Issue 24 Pages 245427
Keywords A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
Abstract The strain fields of periodically buckled graphene induce a periodic pseudomagnetic field (PMF) that modifies the electronic band structure. From the geometry, amplitude, and period of the periodic pseudomagnetic field, we determine the necessary conditions to access the regime of correlated phases by examining the band flattening. As compared to twisted bilayer graphene the proposed system has the advantages that (1) only a single layer of graphene is needed, (2) one is not limited to hexagonal superlattices, and (3) narrower flat bandwidth and larger separation between flat bands can be induced. We, therefore, propose that periodically strained graphene single layers can become a platform for the exploration of exotic many-body phases.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000602844600007 Publication Date 2020-12-28
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9969; 2469-9950 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.7 Times cited 11 Open Access OpenAccess
Notes ; S.P.M. is supported by the Flemish Science Foundation (FWO). We thank E. Y. Andrei, Y. Jiang, and J. Mao for fruitful discussions. ; Approved (up) Most recent IF: 3.7; 2020 IF: 3.836
Call Number UA @ admin @ c:irua:175021 Serial 6684
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Author Shekarforoush, S.; Jalali, H.; Yagmurcukardes, M.; Milošević, M.V.; Neek-Amal, M.
Title Optoelectronic properties of confined water in angstrom-scale slits Type A1 Journal article
Year 2020 Publication Physical Review B Abbreviated Journal Phys Rev B
Volume 102 Issue 23 Pages 235406
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The optoelectronic properties of confined water form one of the most active research areas in the past few years. Here we present the multiscale methodology to discern the out-of-plane electronic and dipolar dielectric constants (epsilon(el)(perpendicular to) and epsilon(diP)(perpendicular to)) of strongly confined water. We reveal that epsilon(perpendicular to el) and epsilon(diP)(perpendicular to) become comparable for water confined in angstrom-scale channels (with a height of less than 15 angstrom) within graphene (GE) and hexagonal boron nitride (hBN) bilayers. Channel height (h) associated with a minimum in both epsilon(e)(l)(perpendicular to) and epsilon(dip)(perpendicular to) is linked to the formation of the ordered structure of ice for h approximate to (7 -7.5) angstrom. The recently measured total dielectric constant epsilon(T)(perpendicular to) of nanoconfined water [L. Fumagalli et al., Science 360, 1339 (2018)] is corroborated by our results. Furthermore, we evaluate the contribution from the encapsulating membranes to the dielectric properties, as a function of the interlayer spacing, i.e., the height of the confining channel for water. Finally, we conduct analysis of the optical properties of both confined water and GE membranes, and show that the electron energy loss function of confined water strongly differs from that of bulk water.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000595856100004 Publication Date 2020-12-04
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9969; 2469-9950 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.7 Times cited 1 Open Access
Notes ; This work was supported by the Research Foundation – Flanders (FWO). M.Y. gratefully acknowledges his FWO postdoctoral mandate. ; Approved (up) Most recent IF: 3.7; 2020 IF: 3.836
Call Number UA @ admin @ c:irua:175051 Serial 6695
Permanent link to this record
 
 
Author Wozniak, T.; Faria, P.E., Jr.; Seifert, G.; Chaves, A.; Kunstmann, J.
Title Exciton g factors of van der Waals heterostructures from first-principles calculations Type A1 Journal article
Year 2020 Publication Physical Review B Abbreviated Journal Phys Rev B
Volume 101 Issue 23 Pages 235408-235411
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract External fields are a powerful tool to probe optical excitations in a material. The linear energy shift of an excitation in a magnetic field is quantified by its effective g factor. Here we show how exciton g factors and their sign can be determined by converged first-principles calculations. We apply the method to monolayer excitons in semiconducting transition metal dichalcogenides and to interlayer excitons in MoSe2/WSe2 heterobilayers and obtain good agreement with recent experimental data. The precision of our method allows us to assign measured g factors of optical peaks to specific transitions in the band structure and also to specific regions of the samples. This revealed the nature of various, previously measured interlayer exciton peaks. We further show that, due to specific optical selection rules, g factors in van der Waals heterostructures are strongly spin and stacking-dependent. The calculation of orbital angular momenta requires the summation over hundreds of bands, indicating that for the considered two-dimensional materials the basis set size is a critical numerical issue. The presented approach can potentially be applied to a wide variety of semiconductors.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000537315100009 Publication Date 2020-06-03
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9969; 2469-9950 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.7 Times cited Open Access
Notes Approved (up) Most recent IF: 3.7; 2020 IF: 3.836
Call Number UA @ admin @ c:irua:170219 Serial 7944
Permanent link to this record
 
 
Author Siriwardane, E.M.D.; Demiroglu, I.; Sevik, C.; Peeters, F.M.; Çakir, D.
Title Assessment of sulfur-functionalized MXenes for li-ion battery applications Type A1 Journal article
Year 2020 Publication Journal Of Physical Chemistry C Abbreviated Journal J Phys Chem C
Volume 124 Issue 39 Pages 21293-21304
Keywords A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Abstract The surface termination of MXenes greatly determines the electrochemical properties and ion kinetics on their surfaces. So far, hydroxyl-, oxygen-, and fluorine-terminated MXenes have been widely studied for energy storage applications. Recently, sulfur-functionalized MXene structures, which possess low diffusion barriers, have been proposed as candidate materials to enhance battery performance. We performed first-principles calculations on the structural, stability, electrochemical, and ion dynamic properties of Li-adsorbed sulfur-functionalized groups 3B, 4B, 5B, and 6B transition-metal (M)-based MXenes (i.e., M2CS2 with M = Sc, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W). We performed phonon calculations, which indicated that all of the above M2CS2 MXenes, except for Sc, are dynamically stable at T = 0 K. The ground-state structure of each M2CS2 monolayer depends on the type of M atom. For instance, while sulfur prefers to sit at the FCC site on Ti2CS2, it occupies the HCP site of Cr-based MXene. We determined the Li adsorption configurations at different concentrations using the cluster expansion method. The highest maximum open-circuit voltages were computed for the group 4B element (i.e., Ti, Zr, and Hf)-based M2CS2, which are larger than 2.1 V, while their average voltages are approximately 1 V. The maximum voltage for the group 6B element (i.e., Cr, Mo, W)-based M2CS2 is less than 1 V, and the average voltage is less than 0.71 V. We found that S functionalization is helpful for capacity improvements over the O-terminated MXenes. In this respect, the computed storage gravimetric capacity may reach up to 417.4 mAh/g for Ti2CS2 and 404.5 mAh/g for V2CS2. Ta-, Cr-, Mo-, and W-based M2CS2 MXenes show very low capacities, which are less than 100 mAh/g. The Li surface diffusion energy barriers for all of the considered MXenes are less than 0.22 eV, which is favorable for high charging and discharging rates. Finally, ab initio molecular dynamic simulations performed at 400 K and bond-length analysis with respect to Li concentration verify that selected promising systems are robust against thermally induced perturbations that may induce structural transformations or distortions and undesirable Li release.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000577151900008 Publication Date 2020-09-01
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1932-7447; 1932-7455 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.7 Times cited 15 Open Access
Notes ; Computational resources were provided by the HPC infrastructure of the University of Antwerp (CalcUA), a division of the Flemish Supercomputer Center (VSC), which is funded by the Hercules Foundation. This work was supported, in part, by The Scientific and Technological Research Council of Turkey (TUBITAK) under contract no. 118F512 and the Air Force Office of Scientific Research under award no. FA9550-19-1-7048. This work was performed in part at the Center for Nanoscale Materials, a U.S. Department of Energy Office of Science User. Use of the Center for Nanoscale Materials, an Office of Science user facility, was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under contract no. DE-AC02-06CH11357. This work was supported, in part, by The Scientific and Technological Research Council of Turkey (TUBITAK) under contract no. 118C026. ; Approved (up) Most recent IF: 3.7; 2020 IF: 4.536
Call Number UA @ admin @ c:irua:172693 Serial 6452
Permanent link to this record
 
 
Author Gjerding, M.N.; Cavalcante, L.S.R.; Chaves, A.; Thygesen, K.S.
Title Efficient Ab initio modeling of dielectric screening in 2D van der Waals materials : including phonons, substrates, and doping Type A1 Journal article
Year 2020 Publication Journal Of Physical Chemistry C Abbreviated Journal J Phys Chem C
Volume 124 Issue 21 Pages 11609-11616
Keywords A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Abstract The quantum electrostatic heterostructure (QEH) model allows for efficient computation of the dielectric screening properties of layered van der Waals (vdW)-bonded heterostructures in terms of the dielectric functions of the individual two-dimensional (2D) layers. Here, we extend the QEH model by including (1) contributions to the dielectric function from infrared active phonons in the 2D layers, (2) screening from homogeneous bulk substrates, and (3) intraband screening from free carriers in doped 2D semiconductor layers. We demonstrate the potential of the extended QEH model by calculating the dispersion of coupled phonons in multilayer stacks of hexagonal boron-nitride (hBN), the strong hybridization of plasmons and optical phonons in graphene/hBN heterostructures, the effect of substrate screening on the exciton series of monolayer MoS2, and the properties of hyperbolic plasmons in a doped phosphorene sheet. The new QEH code is distributed as a Python package with a simple command line interface and a comprehensive library of dielectric building blocks for the most common 2D materials, providing an efficient open platform for dielectric modeling of realistic vdW heterostructures.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000614615900022 Publication Date 2020-05-04
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1932-7447; 1932-7455 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.7 Times cited Open Access
Notes Approved (up) Most recent IF: 3.7; 2020 IF: 4.536
Call Number UA @ admin @ c:irua:176187 Serial 7852
Permanent link to this record
 
 
Author Cadorim, L.R.; de Toledo, L.V.; Ortiz, W.A.; Berger, J.; Sardella, E.
Title Closed vortex state in three-dimensional mesoscopic superconducting films under an applied transport current Type A1 Journal article
Year 2023 Publication Physical review B Abbreviated Journal Phys Rev B
Volume 107 Issue 9 Pages 094515-94518
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract By using the full 3D generalized time-dependent Ginzbug-Landau equation, we study a long superconducting film of finite width and thickness under an applied transport current. We show that, for sufficiently large thickness, the vortices and the antivortices become curved before they annihilate each other. As they approach the center of the sample, their ends combine, producing a single closed vortex. We also determine the critical values of the thickness for which the closed vortex sets in for different values of the Ginzburg-Ladau parameter. Finally, we propose a model of how to detect a closed vortex experimentally.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000957055800002 Publication Date 2023-03-20
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9969; 2469-9950 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.7 Times cited Open Access Not_Open_Access
Notes Approved (up) Most recent IF: 3.7; 2023 IF: 3.836
Call Number UA @ admin @ c:irua:196079 Serial 7673
Permanent link to this record
 
 
Author Shafiei, M.; Fazileh, F.; Peeters, F.M.; Milošević, M.V.
Title High Chern number in strained thin films of dilute magnetic topological insulators Type A1 Journal article
Year 2023 Publication Physical review B Abbreviated Journal
Volume 107 Issue 19 Pages 195119-6
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The quantum anomalous Hall effect was first observed experimentally by doping the Bi2Se3 materials family with chromium, where 5% doping induces an exchange field of around 0.1 eV. In ultrathin films, a topological phase transition from a normal insulator to a Chern insulator can be induced with an exchange field proportional to the hybridization gap. Subsequent transitions to states with higher Chern numbers require an exchange field larger than the (bulk) band gap, but are prohibited in practice by the detrimental effects of higher doping levels. Here, we show that threshold doping for these phase transitions in thin films is controllable by strain. As a consequence, higher Chern states can be reached with experimentally feasible doping, sufficiently dilute for the topological insulator to remain structurally stable. Such a facilitated realization of higher Chern insulators opens prospects for multichannel quantum computing, higher-capacity circuit interconnects, and energy-efficient electronic devices at elevated temperatures.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000995111000003 Publication Date 2023-05-11
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9969; 2469-9950 ISBN Additional Links UA library record; WoS full record
Impact Factor 3.7 Times cited Open Access OpenAccess
Notes Approved (up) Most recent IF: 3.7; 2023 IF: 3.836
Call Number UA @ admin @ c:irua:197295 Serial 8820
Permanent link to this record
 
 
Author Ahmadkhani, S.; Alihosseini, M.; Ghasemi, S.; Ahmadabadi, I.; Hassani, N.; Peeters, F.M.; Neek-Amal, M.
Title Multiband flattening and linear Dirac band structure in graphene with impurities Type A1 Journal article
Year 2023 Publication Physical review B Abbreviated Journal
Volume 107 Issue 7 Pages 075401-75408
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Flat bands in the energy spectrum have attracted a lot of attention in recent years because of their unique properties and promising applications. Special arrangement of impurities on monolayer graphene are proposed to generate multiflat bands in the electronic band structure. In addition to the single midgap states in the spectrum of graphene with low hydrogen density, we found closely spaced bands around the Fermi level with increasing impurity density, which are similar to discrete lines in the spectrum of quantum dots, as well as the unusual Landau-level energy spectrum of graphene in the presence of a strong magnetic field. The presence of flat bands crucially depends on whether or not there are odd or even electrons of H(F) atoms bound to graphene. Interestingly, we found that a fully hydrogenated (fluoridated) of a hexagon of graphene sheet with six hydrogen (fluorine) atoms sitting on top and bottom in consecutive order exhibits Dirac cones in the electronic band structure with a 20% smaller Fermi velocity as compared to the pristine graphene. Functionalizing graphene introduces various C-C bond lengths resulting in nonuniform strains. Such a nonuniform strain may induce a giant pseudomagnetic field in the system, resulting in quantum Hall effect.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000994364500006 Publication Date 2023-02-02
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9969; 2469-9950 ISBN Additional Links UA library record; WoS full record
Impact Factor 3.7 Times cited Open Access OpenAccess
Notes Approved (up) Most recent IF: 3.7; 2023 IF: 3.836
Call Number UA @ admin @ c:irua:197431 Serial 8822
Permanent link to this record
 
 
Author Zuniga-Puelles, E.; Levytskyi, V.; Özden, A.; Guerel, T.; Bulut, N.; Himcinschi, C.; Sevik, C.; Kortus, J.; Gumeniuk, R.
Title Thermoelectric properties and scattering mechanisms in natural PbS Type A1 Journal article
Year 2023 Publication Physical review B Abbreviated Journal
Volume 107 Issue 19 Pages 195203-195215
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract X-ray diffraction and energy dispersive x-ray spectroscopic analyses showed a natural galena (PbS) crystal from Freiberg in Saxony (Germany) to be a single phase specimen [rock salt (NaCl) structure type, space group Fm3m, a = 5.932(1) angstrom] with stoichiometric composition and an enhanced dislocation density (8 approximate to 1011 cm-2). The latter parameter leads to an increase of the electrical resistivity in the high-temperature regime, as well as to the appearance of phonon resonance with a characteristic frequency coPR = 3.8(1) THz. Being in the same range (i.e., 3-5.5 THz) with the sulfur optical modes of highest group velocities, it results in a drastic reduction (by similar to 75%) of thermal conductivity (K) at lower temperatures (i.e., < 100 K), as well as in the appearance of a characteristic minimum in K at T approximate to 30 K. Furthermore, the studied galena is characterized by phonon-drag behavior and by temperature dependent switch of the charge carrier scattering mechanism regime (i.e., scattering on dislocations for T < 100 K, on acoustic phonons for 100 K < T < 170 K and on both acoustic and optical phonons for 170 K < T < 300 K). The combined theoretical calculation and optical spectroscopic study confirm this mineral to be a direct gap degenerate semiconductor. The possible origins of the second-order Raman spectrum are discussed.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 001009980400008 Publication Date 2023-05-30
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9969; 2469-9950 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.7 Times cited Open Access Not_Open_Access
Notes Approved (up) Most recent IF: 3.7; 2023 IF: 3.836
Call Number UA @ admin @ c:irua:197808 Serial 8943
Permanent link to this record
 
 
Author Linard, F.J.A.; Moura, V.N.; Covaci, L.; Milošević, M.V.; Chaves, A.
Title Wave-packet scattering at a normal-superconductor interface in two-dimensional materials : a generalized theoretical approach Type A1 Journal article
Year 2023 Publication Physical review B Abbreviated Journal
Volume 107 Issue 16 Pages 165306-165309
Keywords A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
Abstract A wave-packet time evolution method, based on the split-operator technique, is developed to investigate the scattering of quasiparticles at a normal-superconductor interface of arbitrary profile and shape. As a practical application, we consider a system where low-energy electrons can be described as Dirac particles, which is the case for most two-dimensional materials, such as graphene and transition-metal dichalcogenides. However, the method is easily adapted for other cases such as electrons in few-layer black phosphorus or any Schrodinger quasiparticles within the effective mass approximation in semiconductors. We employ the method to revisit Andreev reflection in mono-, bi-, and trilayer graphene, where specular-and retro-reflection cases are observed for electrons scattered by a steplike superconducting region. The effect of opening a zero-gap channel across the superconducting region on the electron and hole scattering is also addressed, as an example of the versatility of the technique proposed here.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000974675700006 Publication Date 2023-04-14
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9969; 2469-9950 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.7 Times cited Open Access OpenAccess
Notes Approved (up) Most recent IF: 3.7; 2023 IF: 3.836
Call Number UA @ admin @ c:irua:196709 Serial 8954
Permanent link to this record
 
 
Author Claes, J.; Partoens, B.; Lamoen, D.
Title Decoupled DFT-1/2 method for defect excitation energies Type A1 Journal Article
Year 2023 Publication Physical Review B Abbreviated Journal Phys. Rev. B
Volume 108 Issue 12 Pages 125306
Keywords A1 Journal Article; Condensed Matter Theory (CMT) ;
Abstract The DFT-1/2 method is a band-gap correction with GW precision at a density functional theory (DFT) computational cost. The method was also extended to correct the gap between defect levels, allowing for the calculation of optical transitions. However, this method fails when the atomic character of the occupied and unoccupied defect levels is similar as we illustrate by two examples, the tetrahedral hydrogen interstitial and the negatively charged vacancy in diamond. We solve this problem by decoupling the effect of the occupied and unoccupied defect levels and call this the decoupled DFT-1/2 method for defects.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 001089302800003 Publication Date 2023-09-25
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9950 ISBN Additional Links UA library record; WoS full record
Impact Factor 3.7 Times cited Open Access Not_Open_Access
Notes This work was supported by the FWO (Research Foundation-Flanders), Project No. G0D1721N. This work was performed in part using HPC resources from the VSC (Flemish Supercomputer Center) and the HPC infrastructure of the University of Antwerp (CalcUA), both funded by the FWO-Vlaanderen and the Flemish Government department EWI (Economie, Wetenschap & Innovatie). Approved (up) Most recent IF: 3.7; 2023 IF: 3.836
Call Number CMT @ cmt @c:irua:201287 Serial 8976
Permanent link to this record
 
 
Author Bekaert, J.
Title Phonon-mediated superconductivity in ternary silicides X₄ CoSi (X = Nb, Ta) Type A1 Journal article
Year 2023 Publication Physical review B Abbreviated Journal
Volume 108 Issue 13 Pages 134504-134507
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The superconducting properties of two recently synthesized ternary silicides with unit formula X<sub>4</sub>CoSi (X = Nb, Ta) are investigated through ab initio calculations combined with Eliashberg theory. Interestingly, their crystal structure comprises interlocking honeycomb networks of Nb/Ta atoms. Nb<sub>4</sub>CoSi is found to harbor better conditions for phonon-mediated superconductivity, as it possesses a higher density of states at the Fermi level, fostering stronger electron-phonon coupling. The superconducting critical temperatures (T<sub>c</sub>) follow the same trend, with Nb<sub>4</sub>CoSi having a twice higher value than Ta<sub>4</sub>CoSi. Furthermore, the calculated T<sub>c</sub> values (5.9 K vs 3.1 K) agree excellently with the experimentally obtained ones, establishing superconductivity in this new materials class as mediated by the electron-phonon coupling. Furthermore, my calculations show that the superconducting properties of these compounds do not simply correlate with the parameters of their honeycomb networks, contrary to proposals raised in the literature. Rather, their complete fermiology and phonon spectrum should be taken into account in order to explain their respective superconducting properties.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 001140080300003 Publication Date 2023-10-17
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9969; 2469-9950 ISBN Additional Links UA library record; WoS full record
Impact Factor 3.7 Times cited Open Access
Notes Approved (up) Most recent IF: 3.7; 2023 IF: 3.836
Call Number UA @ admin @ c:irua:201445 Serial 9071
Permanent link to this record
 
 
Author Santos-Castro, G.; Pandey, T.; Bruno, C.H.V.; Santos Caetano, E.W.; Milošević, M.V.; Chaves, A.; Freire, V.N.
Title Silicon and germanium adamantane and diamantane monolayers as two-dimensional anisotropic direct-gap semiconductors Type A1 Journal article
Year 2023 Publication Physical review B Abbreviated Journal
Volume 108 Issue 3 Pages 035302-35310
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Structural and electronic properties of silicon and germanium monolayers with two different diamondoid crystal structures are detailed ab initio. Our results show that, despite Si and Ge being well-known indirect gap semiconductors in their bulk form, their adamantane and diamantane monolayers can exhibit optically active direct gap in the visible frequency range, with highly anisotropic effective masses, depending on the monolayer crystal structure. Moreover, we reveal that gaps in these materials are highly tunable with applied strain. These stable monolayer forms of Si and Ge are therefore expected to help bridging the gap between the fast growing area of opto-electronics in two-dimensional materials and the established silicon-based technologies.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 001074455300012 Publication Date 2023-07-05
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9969; 2469-9950 ISBN Additional Links UA library record; WoS full record
Impact Factor 3.7 Times cited Open Access
Notes Approved (up) Most recent IF: 3.7; 2023 IF: 3.836
Call Number UA @ admin @ c:irua:200348 Serial 9089
Permanent link to this record
 
 
Author Lima, I.L.C.; Milošević, M.V.; Peeters, F.M.; Chaves, A.
Title Tuning of exciton type by environmental screening Type A1 Journal article
Year 2023 Publication Physical review B Abbreviated Journal
Volume 108 Issue 11 Pages 115303-115308
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract We theoretically investigate the binding energy and electron-hole (e-h) overlap of excitonic states confined at the interface between two-dimensional materials with type-II band alignment, i.e., with lowest conduction and highest valence band edges placed in different materials, arranged in a side-by-side planar heterostructure. We propose a variational procedure within the effective mass approximation to calculate the exciton ground state and apply our model to a monolayer MoS2/WS2 heterostructure. The role of nonabrupt interfaces between the materials is accounted for in our model by assuming a WxMo1-xS2 alloy around the interfacial region. Our results demonstrate that (i) interface-bound excitons are energetically favorable only for small interface thickness and/or for systems under high dielectric screening by the materials surrounding the monolayer, and that (ii) the interface exciton binding energy and its e-h overlap are controllable by the interface width and dielectric environment.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 001077758300002 Publication Date 2023-09-08
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9969; 2469-9950 ISBN Additional Links UA library record; WoS full record
Impact Factor 3.7 Times cited Open Access
Notes Approved (up) Most recent IF: 3.7; 2023 IF: 3.836
Call Number UA @ admin @ c:irua:200356 Serial 9110
Permanent link to this record
 
 
Author Galvan Moya, J.E.; Nelissen, K.; Peeters, F.M.
Title Structural ordering of self-assembled clusters with competing interactions : transition from faceted to spherical clusters Type A1 Journal article
Year 2015 Publication Langmuir: the ACS journal of surfaces and colloids Abbreviated Journal Langmuir
Volume 31 Issue 31 Pages 917-924
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The self-assembly of nanoparticles into clusters and the effect of the different parameters of the competing interaction potential on it are investigated. For a small number of particles, the structural organization of the clusters is almost unaffected by the attractive part of the potential, and for an intermediate number of particles the configuration strongly depends on the strength of it. The cluster size is controlled by the range of the interaction potential, and the structural arrangement is guided by the strength of the potential: i.e., the self-assembled cluster transforms from a faceted configuration at low strength to a spherical shell-like structure at high strength. Nonmonotonic behavior of the cluster size is found by increasing the interaction range. An approximate analytical expression is obtained that predicts the smallest cluster for a specific set of potential parameters. A Mendeleev-like table is constructed for different values of the strength and range of the attractive part of the potential in order to understand the structural ordering of the ground-state configuration of the self-assembled clusters.
Address
Corporate Author Thesis
Publisher Place of Publication Washington, D.C. Editor
Language Wos 000348689700005 Publication Date 2014-12-30
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0743-7463;1520-5827; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.833 Times cited 4 Open Access
Notes ; This work was supported by the Flemish Science Foundation (FWO-Vl) and the Methusalem programme of the Flemish government. Computational resources were provided by the HPC infrastructure of the University of Antwerp (CalcUA), a division of the Flemish Supercomputer Center (VSC). ; Approved (up) Most recent IF: 3.833; 2015 IF: 4.457
Call Number c:irua:125292 Serial 3243
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Author Stosic, D.; Mulkers, J.; Van Waeyenberge, B.; Ludermir, T.B.; Milošević, M.V.
Title Paths to collapse for isolated skyrmions in few-monolayer ferromagnetic films Type A1 Journal article
Year 2017 Publication Physical review B Abbreviated Journal Phys Rev B
Volume 95 Issue 21 Pages 214418
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Magnetic skyrmions are topological spin configurations in materials with chiral Dzyaloshinskii-Moriya interaction (DMI), that are potentially useful for storing or processing information. To date, DMI has been found in few bulk materials, but can also be induced in atomically thin magnetic films in contact with surfaces with large spin-orbit interactions. Recent experiments have reported that isolated magnetic skyrmions can be stabilized even near room temperature in few-atom-thick magnetic layers sandwiched between materials that provide asymmetric spin-orbit coupling. Here we present the minimum-energy path analysis of three distinct mechanisms for the skyrmion collapse, based on ab initio input and the performed atomic-spin simulations. We focus on the stability of a skyrmion in three atomic layers of Co, either epitaxial on the Pt(111) surface or within a hybrid multilayer where DMI nontrivially varies per monolayer due to competition between different symmetry breaking from two sides of the Co film. In laterally finite systems, their constrained geometry causes poor thermal stability of the skyrmion toward collapse at the boundary, which we show to be resolved by designing the high-DMI structure within an extended film with lower or no DMI.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000404015500001 Publication Date 2017-06-23
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9950 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 48 Open Access
Notes This work was supported by the Research Foundation, Flanders (FWO-Vlaanderen) and Brazilian agency CNPq (Grants No. 442668/2014-7 and No. 140840/2016-8). Approved (up) Most recent IF: 3.836
Call Number CMT @ cmt @c:irua:144865 Serial 4704
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Author Callewaert, V.; Saniz, R.; Barbiellini, B.; Bansil, A.; Partoens, B.
Title Application of the weighted-density approximation to the accurate description of electron-positron correlation effects in materials Type A1 Journal article
Year 2017 Publication Physical review B Abbreviated Journal Phys Rev B
Volume 96 Issue 8 Pages 085135
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract We discuss positron-annihilation lifetimes for a set of illustrative bulk materials within the framework of the weighted-density approximation (WDA). The WDA can correctly describe electron-positron correlations in strongly inhomogeneous systems, such as surfaces, where the applicability of (semi-)local approximations is limited. We analyze the WDA in detail and show that the electrons which cannot screen external charges efficiently, such as the core electrons, cannot be treated accurately via the pair correlation of the homogeneous electron gas. We discuss how this problem can be addressed by reducing the screening in the homogeneous electron gas by adding terms depending on the gradient of the electron density. Further improvements are obtained when core electrons are treated within the LDA and the valence electron using the WDA. Finally, we discuss a semiempirical WDA-based approach in which a sum rule is imposed to reproduce the experimental lifetimes.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000408342600003 Publication Date 2017-08-24
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9950 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 6 Open Access
Notes Fonds Wetenschappelijk Onderzoek, G. 0224.14N ; U.S. Department of Energy, DE-FG02-07ER46352 DE-AC02-05CH11231 DE-SC0012575 ; Approved (up) Most recent IF: 3.836
Call Number CMT @ cmt @c:irua:145703 Serial 4703
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Author da Costa, D.R.; Zarenia, M.; Chaves, A.; Farias, G.A.; Peeters, F.M.
Title Magnetic field dependence of energy levels in biased bilayer graphene quantum dots Type A1 Journal article
Year 2016 Publication Physical review B Abbreviated Journal Phys Rev B
Volume 93 Issue 93 Pages 085401
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Using the tight-binding approach, we study the influence of a perpendicular magnetic field on the energy levels of hexagonal, triangular, and circular bilayer graphene (BLG) quantum dots (QDs) with zigzag and armchair edges. We obtain the energy levels for AB (Bernal)-stacked BLG QDs in both the absence and the presence of a perpendicular electric field (i.e., biased BLG QDs). We find different regions in the spectrum of biased QDs with respect to the crossing point between the lowest-electron and -hole Landau levels of a biased BLG sheet. Those different regions correspond to electron states that are localized at the center, edge, or corner of the BLG QD. Quantum Hall corner states are found to be absent in circular BLG QDs. The spatial symmetry of the carrier density distribution is related to the symmetry of the confinement potential, the position of zigzag edges, and the presence or absence of interlayer inversion symmetry.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000369402400008 Publication Date 2016-02-01
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9950 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 22 Open Access
Notes ; This work was financially supported by CNPq, under Contract No. NanoBioEstruturas 555183/2005-0, PRONEX/FUNCAP, CAPES Foundation under the Process No. BEX 7178/13-1, the Flemish Science Foundation (FWO-Vl), the Bilateral programme between CNPq and FWO-Vl, and the Brazilian Program Science Without Borders (CsF). ; Approved (up) Most recent IF: 3.836
Call Number c:irua:131623 Serial 4038
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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.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000377298600006 Publication Date 2016-06-06
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9950 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 28 Open Access
Notes ; ; Approved (up) Most recent IF: 3.836
Call Number c:irua:133919 Serial 4081
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Author Bacaksiz, C.; Cahangirov, S.; Rubio, A.; Senger, R.T.; Peeters, F.M.; Sahin, H.
Title Bilayer SnS2 : tunable stacking sequence by charging and loading pressure Type A1 Journal article
Year 2016 Publication Physical review B Abbreviated Journal Phys Rev B
Volume 93 Issue 93 Pages 125403
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Employing density functional theory-based methods, we investigate monolayer and bilayer structures of hexagonal SnS2, which is a recently synthesized monolayer metal dichalcogenide. Comparison of the 1H and 1T phases of monolayer SnS2 confirms the ground state to be the 1T phase. In its bilayer structure we examine different stacking configurations of the two layers. It is found that the interlayer coupling in bilayer SnS2 is weaker than that of typical transition-metal dichalcogenides so that alternative stacking orders have similar structural parameters and they are separated with low energy barriers. A possible signature of the stacking order in the SnS2 bilayer has been sought in the calculated absorbance and reflectivity spectra. We also study the effects of the external electric field, charging, and loading pressure on the characteristic properties of bilayer SnS2. It is found that (i) the electric field increases the coupling between the layers at its preferred stacking order, so the barrier height increases, (ii) the bang gap value can be tuned by the external E field and under sufficient E field, the bilayer SnS2 can become a semimetal, (iii) the most favorable stacking order can be switched by charging, and (iv) a loading pressure exceeding 3 GPa changes the stacking order. The E-field tunable band gap and easily tunable stacking sequence of SnS2 layers make this 2D crystal structure a good candidate for field effect transistor and nanoscale lubricant applications.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000371405000005 Publication Date 2016-03-03
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9950;2469-9969; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 38 Open Access
Notes ; The calculations were performed at TUBITAK ULAKBIM, High Performance and Grid Computing Center (TR-Grid e-Infrastructure). C.B., H.S., and R.T.S. acknowledge support from TUBITAK Project No. 114F397. H.S. is supported by an FWO Pegasus Marie Curie Fellowship. S.C. and A.R. acknowledge financial support from the Marie Curie grant FP7-PEOPLE-2013-IEF Project No. 628876, the European Research Council (ERC-2010-AdG-267374), and Spanish grant Grupos Consolidados (IT578-13). S.C. acknowledges support from the Scientific and Technological Research Council of Turkey (TUBITAK) under Project No. 115F388. ; Approved (up) Most recent IF: 3.836
Call Number UA @ lucian @ c:irua:132345 Serial 4144
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Author Van der Donck, M.; Peeters, F.M.; Van Duppen, B.
Title Comment on “Creating in-plane pseudomagnetic fields in excess of 1000 T by misoriented stacking in a graphene bilayer” Type Editorial
Year 2016 Publication Physical review B Abbreviated Journal Phys Rev B
Volume 93 Issue 93 Pages 247401
Keywords Editorial; Condensed Matter Theory (CMT)
Abstract In a recent paper [Phys. Rev. B 89, 125418 (2014)], the authors argue that it is possible to map the electronic properties of twisted bilayer graphene to those of bilayer graphene in an in-plane magnetic field. However, their description of the low-energy dynamics of twisted bilayer graphene is restricted to the extended zone scheme and therefore neglects the effects of the superperiodic structure. If the energy spectrum is studied in the supercell Brillouin zone, we find that the comparison with an in-plane magnetic field fails because (i) the energy spectra of the two situations exhibit different symmetries and (ii) the low-energy spectra are very different.
Address
Corporate Author Thesis
Publisher Amer physical soc Place of Publication College pk Editor
Language Wos 000377802200009 Publication Date 2016-06-14
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9950;2469-9969; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 6 Open Access
Notes ; ; Approved (up) Most recent IF: 3.836
Call Number UA @ lucian @ c:irua:134601 Serial 4151
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Author Roy, P.; Torun, E.; de Groot, R.A.
Title Effect of doping and elastic properties in (Mn,Fe)2(Si,P) Type A1 Journal article
Year 2016 Publication Physical review B Abbreviated Journal Phys Rev B
Volume 93 Issue 93 Pages 094110
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Mixed magnetism (the coexistence of strong and weak magnetism in one material) is regarded as the origin of the giant magnetocaloric effect (GMCE). A good example is (Mn,Fe)(2)(Si,P), which is established as one of the best magnetocaloric materials available. Tuning the material properties are essential for optimizing its performance, and a straightforward way to do that is by doping. In this article, an ab initio electronic structure method was used to calculate the structure and magnetic properties of 3d-transition-metal-doped (Mn,Fe)(2)(Si,P) materials for magnetocaloric applications (transition metals are Cr, Co, Mn, Ni, Cu). For a steady performance, the material should be mechanically stable. A detailed analysis of the elastic constants shows that the mechanical stability of the (Mn,Fe)(2)(Si,P) system increases significantly by doping with boron without affecting the magnetic properties. Insights of the influence of doping enable future studies to understand and predict bettermagnetocaloric materials.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000372712100001 Publication Date 2016-03-25
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9950;2469-9969; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 9 Open Access
Notes ; This work is part of an Industrial Partnership Programme (IPP I28) of Fundamenteel Onderzoek der Materie (FOM) (The Netherlands) and co-financed by BASF New Business. The authors would like to thank Phuong Thao Nguyen and Dr. Gilles A. de Wijs for very useful discussions. ; Approved (up) Most recent IF: 3.836
Call Number UA @ lucian @ c:irua:133192 Serial 4164
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Author Bakalov, P.; Esfahani, D.N.; Covaci, L.; Peeters, F.M.; Tempere, J.; Locquet, J.-P.
Title Electric-field-driven Mott metal-insulator transition in correlated thin films : an inhomogeneous dynamical mean-field theory approach 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 165112
Keywords A1 Journal article; Theory of quantum systems and complex systems; Condensed Matter Theory (CMT)
Abstract Simulations are carried out based on the dynamical mean-field theory (DMFT) in order to investigate the properties of correlated thin films for various values of the chemical potential, temperature, interaction strength, and applied transverse electric field. Application of a sufficiently strong field to a thin film at half filling leads to the appearance of conducting regions near the surfaces of the film, whereas in doped slabs the application of a field leads to a conductivity enhancement on one side of the film and a gradual transition to the insulating state on the opposite side. In addition to the inhomogeneous DMFT, a local density approximation (LDA) is considered in which the particle density n, quasiparticle residue Z, and spectral weight at the Fermi level A(ω=0) of each layer are approximated by a homogeneous bulk environment. A systematic comparison between the two approaches reveals that the less expensive LDA results are in good agreement with the DMFT approach, except close to the metal-to-insulator transition points and in the layers immediately at the film surfaces. LDA values for n are overall more reliable than those for Z and A(ω=0). The hysteretic behavior (memory effect) characteristic of the bulk doping driven Mott transition persists in the slab.
Address
Corporate Author Thesis
Publisher Place of Publication Lancaster, Pa Editor
Language Wos 000373572700002 Publication Date 2016-04-09
Series Editor Series Title Abbreviated Series Title
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 5 Open Access
Notes ; This work was partially funded by the Flemish Fund for Scientific Research (FWO Belgium) under FWO Grant No. G.0520.10 and the joint FWF (Austria)-FWO Grant No. GOG6616N, and by the SITOGA FP7 project. Most of the calculations were performed on KU Leuven's ThinKing HPC cluster provided by the VSC (Flemish Supercomputer Center), funded by the FWO and the Flemish Government-department EWI. ; Approved (up) Most recent IF: 3.836
Call Number UA @ lucian @ c:irua:132872 Serial 4167
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Author Craco, L.; Carara, S.S.; da Silva Pereira, T.A.; Milošević, M.V.
Title Electronic states in an atomistic carbon quantum dot patterned in graphene Type A1 Journal article
Year 2016 Publication Physical review B Abbreviated Journal Phys Rev B
Volume 93 Issue 93 Pages 155417
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract We reveal the emergence of metallicKondo clouds in an atomistic carbon quantum dot, realized as a single-atom junction in a suitably patterned graphene nanoflake. Using density functional dynamical mean-field theory (DFDMFT) we show how correlation effects lead to striking features in the electronic structure of our device, and how those are enhanced by the electron-electron interactions when graphene is patterned at the atomistic scale. Our setup provides a well-controlled environment to understand the principles behind the orbital-selective Kondo physics and the interplay between orbital and spin degrees of freedom in carbon-based nanomaterials, which indicate new pathways for spintronics in atomically patterned graphene.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000373760900004 Publication Date 2016-04-12
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9950;2469-9969; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 6 Open Access
Notes ; L.C.'s work is supported by CNPq (Proc. No. 307487/2014-8). Acknowledgment (L.C.) is also made to G. Seifert for discussions and the Department of Theoretical Chemistry at Technical University Dresden for hospitality. T.A.S.P. thanks PRONEX/CNPq/FAPEMAT 850109/2009 for financial support. M.V.M. acknowledges support from Research Foundation-Flanders (FWO), TOPBOF, and the CAPES-PVE program. ; Approved (up) Most recent IF: 3.836
Call Number UA @ lucian @ c:irua:133260 Serial 4171
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Author Mirzakhani, M.; Zarenia, M.; Ketabi, S.A.; da Costa, D.R.; Peeters, F.M.
Title Energy levels of hybrid monolayer-bilayer graphene quantum dots Type A1 Journal article
Year 2016 Publication Physical review B Abbreviated Journal Phys Rev B
Volume 93 Issue 93 Pages 165410
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Often real samples of graphene consist of islands of both monolayer and bilayer graphene. Bound states in such hybrid quantum dots are investigated for (i) a circular single-layer graphene quantum dot surrounded by an infinite bilayer graphene sheet and (ii) a circular bilayer graphene quantum dot surrounded by an infinite single-layer graphene. Using the continuum model and applying zigzag boundary conditions at the single-layer-bilayer graphene interface, we obtain analytical results for the energy levels and the corresponding wave spinors. Their dependence on perpendicular magnetic and electric fields are studied for both types of quantum dots. The energy levels exhibit characteristics of interface states, and we find anticrossings and closing of the energy gap in the presence of a bias potential.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000373572700004 Publication Date 2016-04-09
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9950;2469-9969; 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 Fonds Wetenschappelijk Onderzoek (FWO)-CNPq project between Flanders and Brazil and the Brazilian Science Without Borders program. ; Approved (up) Most recent IF: 3.836
Call Number UA @ lucian @ c:irua:133261 Serial 4174
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Author da Costa; Zarenia, M.; Chaves, A.; Pereira, J.M., Jr.; Farias, G.A.; Peeters, F.M.
Title Hexagonal-shaped monolayer-bilayer quantum disks in graphene : a tight-binding approach Type A1 Journal article
Year 2016 Publication Physical review B Abbreviated Journal Phys Rev B
Volume 94 Issue 94 Pages 035415
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Using the tight-binding approach, we investigate confined states in two different hybrid monolayer-bilayer systems: (i) a hexagonal monolayer area surrounded by bilayer graphene in the presence of a perpendicularly applied electric field and (ii) a hexagonal bilayer graphene dot surrounded by monolayer graphene. The dependence of the energy levels on dot size and external magnetic field is calculated. We find that the energy spectrum for quantum dots with zigzag edges consists of states inside the gap which range from dot-localized states, edge states, to mixed states coexisting together, whereas for dots with armchair edges, only dot-localized states are observed.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000379502200008 Publication Date 2016-07-11
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9950;2469-9969; 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 financially supported by CNPq, under contract NanoBioEstruturas No. 555183/2005-0, PRONEX/FUNCAP, CAPES Foundation, under the process No. BEX 7178/13-1, the Flemish Science Foundation (FWO-Vl), the Bilateral programme between CNPq and FWO-Vl, the Brazilian Program Science Without Borders (CsF), and the Lemann Foundation. ; Approved (up) Most recent IF: 3.836
Call Number UA @ lucian @ c:irua:134947 Serial 4190
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Author Ghorbanfekr-Kalashami, H.; Neek-Amal, M.; Peeters, F.M.
Title N-doped graphene : polarization effects and structural properties Type A1 Journal article
Year 2016 Publication Physical review B Abbreviated Journal Phys Rev B
Volume 93 Issue 93 Pages 174112
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The structural and mechanical properties of N-doped graphene (NG) are investigated using reactive force field (ReaxFF) potentials in large-scale molecular dynamics simulations. We found that ripples, which are induced by the dopants, change the roughness of NG, which depends on the number of dopants and their local arrangement. For any doping ratio N/C, the NG becomes ferroelectric with a net dipole moment. The formation energy increases nonlinearly with N/C ratio, while the Young's modulus, tensile strength, and intrinsic strain decrease with the number of dopants. Our results for the structural deformation and the thermoelectricity of the NG sheet are in good agreement with recent experiments and ab initio calculations.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000376245900002 Publication Date 2016-05-20
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9950;2469-9969; 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 ESF-Eurographene project CONGRAN, and the Flemish Science Foundation (FWO-Vl). ; Approved (up) Most recent IF: 3.836
Call Number UA @ lucian @ c:irua:134148 Serial 4212
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Author Walter, A.L.; Sahin, H.; Kang, J.; Jeon, K.J.; Bostwick, A.; Horzum, S.; Moreschini, L.; Chang, Y.J.; Peeters, F.M.; Horn, K.; Rotenberg, E.;
Title New family of graphene-based organic semiconductors : an investigation of photon-induced electronic structure manipulation in half-fluorinated graphene Type A1 Journal article
Year 2016 Publication Physical review B Abbreviated Journal Phys Rev B
Volume 93 Issue 93 Pages 075439
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The application of graphene to electronic and optoelectronic devices is limited by the absence of reliable semiconducting variants of this material. A promising candidate in this respect is graphene oxide, with a band gap on the order of similar to 5 eV, however, this has a finite density of states at the Fermi level. Here, we examine the electronic structure of three variants of half-fluorinated carbon on Sic(0001), i.e., the (6 root 3 x 6 root 3) R30 degrees C/SiC “buffer layer,” graphene on this (6 root 3 x 6 root 3) R30 degrees C/SiC buffer layer, and graphene decoupled from the SiC substrate by hydrogen intercalation. Using angle-resolved photoemission, core level photoemission, and x-ray absorption, we show that the electronic, chemical, and physical structure of all three variants is remarkably similar, exhibiting a large band gap and a vanishing density of states at the Fermi level. These results are explained in terms of first-principles calculations. This material thus appears very suitable for applications, even more so since it is prepared on a processing-friendly substrate. We also investigate two separate UV photon-induced modifications of the electronic structure that transform the insulating samples (6.2-eV band gap) into semiconducting (similar to 2.5-eV band gap) and metallic regions, respectively.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000371398000007 Publication Date 2016-02-29
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9950;2469-9969; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 5 Open Access
Notes ; The Advanced Light Source is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the US Department of Energy under Contract No. DE-AC02-05CH11231. Work in Erlangen was supported by the DFG through SPP 1459 “Graphene” and SFB 953 “Synthetic Carbon Allotropes” and by the ESF through the EURO-Graphene project GraphicRF. A.L.W. acknowledges support from the Max-Planck-Gesellschaft, the Donostia International Physics Centre, and the Centro de Fisica de Materiales in San Sebastian, Spain, and Brookhaven National Laboratory under US Department of Energy, Office of Science, Office of Basic Energy Sciences, Contract No. DE-SC0012704. 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), and HPC infrastructure of the University of Antwerp (CalcUA), a division of the Flemish Supercomputer Center (VSC), which is funded by the Hercules foundation. H.S. is supported by a FWO Pegasus-Long Marie Curie Fellowship, and J.K. by a FWO Pegasus-Short Marie Curie Fellowship. Y.J.C. acknowledges support from the National Research Foundation of Korea under Grant No. NRF-2014R1A1A1002868. The authors gratefully acknowledge the work of T. Seyller's group at the Institut fur Physik, Technische Universitat Chemnitz, Germany for providing the samples. ; Approved (up) Most recent IF: 3.836
Call Number UA @ lucian @ c:irua:132352 Serial 4213
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Author Torun, E.; Sahin, H.; Peeters, F.M.
Title Optical properties of GaS-Ca(OH)2 bilayer heterostructure Type A1 Journal article
Year 2016 Publication Physical review B Abbreviated Journal Phys Rev B
Volume 93 Issue 93 Pages 075111
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Finding novel atomically thin heterostructures and understanding their characteristic properties are critical for developing better nanoscale optoelectronic devices. In this study, we investigate the electronic and optical properties of a GaS-Ca(OH)(2) heterostructure using first-principle calculations. The band gap of the GaS-Ca(OH)(2) heterostructure is significantly reduced when compared to those of the isolated constituent layers. Our calculations showthat the GaS-Ca(OH)(2) heterostructure is a type-II heterojunction which can be used to separate photoinduced charge carriers where electrons are localized in GaS and holes in the Ca(OH)(2) layer. This leads to spatially indirect excitons which are important for solar energy and optoelectronic applications due to their long lifetime. By solving the Bethe-Salpeter equation on top of a single shot GW calculation (G(0)W(0)), the dielectric function and optical oscillator strength of the constituent monolayers and the heterostructure are obtained. The oscillator strength of the optical transition for the GaS monolayer is an order of magnitude larger than the Ca(OH)(2) monolayer. We also found that the calculated optical spectra of different stacking types of the heterostructure show dissimilarities, although their electronic structures are rather similar. This prediction can be used to determine the stacking type of ultrathin heterostructures.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000369401000001 Publication Date 2016-02-06
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9950;2469-9969; 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 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), and HPC infrastructure of the University of Antwerp (CalcUA), a division of the Flemish Supercomputer Center (VSC), which is funded by the Hercules foundation. H.S. is supported by a FWO Pegasus long Marie Curie Fellowship. ; Approved (up) Most recent IF: 3.836
Call Number UA @ lucian @ c:irua:131614 Serial 4220
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