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Author Andelkovic, M.; Milovanović, S.P.; Covaci, L.; Peeters, F.M.
Title Double moiré with a twist : supermoiré in encapsulated graphene Type A1 Journal article
Year 2020 Publication Nano Letters Abbreviated Journal Nano Lett
Volume 20 Issue 2 Pages 979
Keywords A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
Abstract A periodic spatial modulation, as created by a moire pattern, has been extensively studied with the view to engineer and tune the properties of graphene. Graphene encapsulated by hexagonal boron nitride (hBN) when slightly misaligned with the top and bottom hBN layers experiences two interfering moire patterns, resulting in a so-called supermoire (SM). This leads to a lattice and electronic spectrum reconstruction. A geometrical construction of the nonrelaxed SM patterns allows us to indicate qualitatively the induced changes in the electronic properties and to locate the SM features in the density of states and in the conductivity. To emphasize the effect of lattice relaxation, we report band gaps at all Dirac-like points in the hole doped part of the reconstructed spectrum, which are expected to be enhanced when including interaction effects. Our result is able to distinguish effects due to lattice relaxation and due to the interfering SM and provides a clear picture on the origin of recently experimentally observed effects in such trilayer heterostuctures.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000514255400021 Publication Date 2020-01-21
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1530-6984 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 10.8 Times cited 48 Open Access OpenAccess
Notes (up) ; This work was funded by FLAGERA project TRANS2DTMD and the Flemish Science Foundation (FWO-Vl) through a postdoc fellowship for S.P.M. The authors acknowledge useful discussions with W. Zihao and K. Novoselov. ; Approved Most recent IF: 10.8; 2020 IF: 12.712
Call Number UA @ admin @ c:irua:168685 Serial 6490
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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 (up) ; 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 Most recent IF: 3.836
Call Number UA @ lucian @ c:irua:132872 Serial 4167
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Author Zha, G.-Q.; Covaci, L.; Peeters, F.M.; Zhou, S.-P.
Title Majorana fermion states and fractional flux periodicity in mesoscopic d-wave superconducting loops with spin-orbit interaction Type A1 Journal article
Year 2014 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 90 Issue 1 Pages 014522
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract We numerically investigate the spin-orbit (SO) coupling effect on the magnetic flux evolution of energy and supercurrent in mesoscopic d-wave superconducting loops by solving the spin-generalized Bogoliubov-de Gennes equations self-consistently. It is found that the energy spectrum splits when the SO interaction is involved and the Majorana zero mode can be realized in the [100] edges of square systems for an appropriate SO coupling strength. Superconducting phase transitions appear when the energy gap closes, accompanied by energy jumps between different energy parabolas in the ground state, which provides a possible mechanism to support fractional flux periodicity of supercurrent. Moreover, in the case of rectangular loops with SO coupling, the jumps of the ground-state energy gradually disappear by increasing the ratio of length to height of the sample, and a paramagnetic response with opposite direction of the screening current around zero flux value can occur in such systems.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000341233800010 Publication Date 2014-07-31
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 7 Open Access
Notes (up) ; This work was supported by National Natural Science Foundation of China under Grants No. 61371020 and No. 61271163, by Visiting Scholar Program of Shanghai Municipal Education Commission, by Innovation Program of Shanghai Municipal Education Commission under Grant No. 13YZ006, and by the Flemish Science Foundation (FWO-Vl). ; Approved Most recent IF: 3.836; 2014 IF: 3.736
Call Number UA @ lucian @ c:irua:119266 Serial 1938
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Author Zha, G.-Q.; Covaci, L.; Peeters, F.M.; Zhou, S.-P.
Title Majorana zero-energy modes and spin current evolution in mesoscopic superconducting loop systems with spin-orbit interaction Type A1 Journal article
Year 2015 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 92 Issue 92 Pages 094516
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The Majorana zero modes and persistent spin current in mesoscopic d-wave-superconducting loops with spin-orbit (SO) interaction are investigated by numerically solving the spin-generalized Bogoliubov-de Gennes equations self-consistently. For some appropriate strength of the SO coupling, Majorana zero-energy states and sharp jumps of the spin-polarized currents can be observed when the highest energy levels cross the Fermi energy in the spectrum, leading to spin currents with opposite chirality flowing near the inner and outer edges of the sample. When the threaded magnetic flux turns on, four flux-dependent patterns of the persistent spin current with step-like features show up, accompanied by Majorana edge modes at flux values where the energy gap closes. Moreover, the Majorana zero mode is highly influenced by the direction of the Zeeman field. A finite in-plane field can lead to the gap opening since the inversion symmetry is broken. Remarkably, multiple Majorana zero-energy states occur in the presence of an out-of-plane field h(z), and the number of steps in the spin current evolution can be effectively tuned by the field strength due to the shift of Majorana zero modes. Finally, when the loop sample contains surface indentation defects, zero-energy modes can always show up in the presence of an appropriate h(z). Interestingly, multiple Majorana states may be present in the system with a corner defect even if h(z) = 0.
Address
Corporate Author Thesis
Publisher Place of Publication Lancaster, Pa Editor
Language Wos 000362081000002 Publication Date 2015-09-30
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 11 Open Access
Notes (up) ; This work was supported by National Natural Science Foundation of China under Grants No. 61371020, No. 61271163, and No. 61571277, by the Visiting Scholar Program of Shanghai Municipal Education Commission, and by the Flemish Science Foundation (FWO-Vl). ; Approved Most recent IF: 3.836; 2015 IF: 3.736
Call Number UA @ lucian @ c:irua:132467 Serial 4203
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Author Chaves, A.; Moura, V.N.; Linard, F.J.A.; Covaci, L.; Milošević, M.V.
Title Tunable magnetic focusing using Andreev scattering in superconductor-graphene hybrid devices Type A1 Journal article
Year 2020 Publication Journal Of Applied Physics Abbreviated Journal J Appl Phys
Volume 128 Issue 12 Pages 124303
Keywords A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
Abstract We perform the wavepacket dynamics simulation of a graphene-based device where propagating electron trajectories are tamed by an applied magnetic field toward a normal/superconductor interface. The magnetic field controls the incidence angle of the incoming electronic wavepacket at the interface, which results in the tunable electron-hole ratio in the reflected wave function due to the angular dependence of the Andreev reflection. Here, mapped control of the quasiparticle trajectories by the external magnetic field not only defines an experimental probe for fundamental studies of the Andreev reflection in graphene but also lays the foundation for further development of magnetic focusing devices based on nanoengineered superconducting two-dimensional materials.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000576393200002 Publication Date 2020-09-28
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0021-8979; 1089-7550 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.2 Times cited 1 Open Access Not_Open_Access
Notes (up) ; This work was supported by the Brazilian Council for Research (CNPq) through the PRONEX/FUNCAP and PQ programs and by the Research Foundation-Flanders (FWO). ; Approved Most recent IF: 3.2; 2020 IF: 2.068
Call Number UA @ admin @ c:irua:172730 Serial 6639
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Author Neek-Amal, M.; Covaci, L.; Shakouri, K.; Peeters, F.M.
Title Electronic structure of a hexagonal graphene flake subjected to triaxial stress Type A1 Journal article
Year 2013 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 88 Issue 11 Pages 115428
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The electronic properties of a triaxially strained hexagonal graphene flake with either armchair or zigzag edges are investigated using molecular dynamics simulations and tight-binding calculations. We found that (i) the pseudomagnetic field in strained graphene flakes is not uniform neither in the center nor at the edge of zigzag terminated flakes, (ii) the pseudomagnetic field is almost zero in the center of armchair terminated flakes but increases dramatically near the edges, (iii) the pseudomagnetic field increases linearly with strain, for strains lower than 15% but increases nonlinearly beyond it, (iv) the local density of states in the center of the zigzag hexagon exhibits pseudo-Landau levels with broken sublattice symmetry in the zeroth pseudo-Landau level, and in addition there is a shift in the Dirac cone due to strain induced scalar potentials, and (v) there is size effect in pseudomagnetic field. This study provides a realistic model of the electronic properties of inhomogeneously strained graphene where the relaxation of the atomic positions is correctly included together with strain induced modifications of the hopping terms up to next-nearest neighbors.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000324690400008 Publication Date 2013-09-24
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 46 Open Access
Notes (up) ; This work was supported by the EU-Marie Curie IIF postdoctoral Fellowship/ 299855 (for M.N.-A.), the ESF EuroGRAPHENE project CONGRAN, the Flemish Science Foundation (FWO-Vl) and the Methusalem Funding of the Flemish government. ; Approved Most recent IF: 3.836; 2013 IF: 3.664
Call Number UA @ lucian @ c:irua:111168 Serial 1011
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Author Esfahani, D.N.; Covaci, L.; Peeters, F.M.
Title Nonlinear response to electric field in extended Hubbard models Type A1 Journal article
Year 2014 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 90 Issue 20 Pages 205121
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The electric-field response of a one-dimensional ring of interacting fermions, where the interactions are described by the extended Hubbard model, is investigated. By using an accurate real-time propagation scheme based on the Chebyshev expansion of the evolution operator, we uncover various nonlinear regimes for a range of interaction parameters that allows modeling of metallic and insulating (either charge density wave or spin density wave insulators) rings. The metallic regime appears at the phase boundary between the two insulating phases and provides the opportunity to describe either weakly or strongly correlated metals. We find that the fidelity susceptibility of the ground state as a function of magnetic flux piercing the ring provides a very good measure of the short-time response. Even completely different interacting regimes behave in a similar manner at short time scales as long as the ground-state fidelity susceptibility is the same. Depending on the strength of the electric field we find various types of responses: persistent currents in the insulating phase, a dissipative regime, or damped Bloch-like oscillations with varying frequencies or even irregular in nature. Furthermore, we also consider the dimerization of the ring and describe the response of a correlated band insulator. In this case the distribution of the energy levels is more clustered and the Bloch-like oscillations become even more irregular.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000345423300002 Publication Date 2014-11-15
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 3 Open Access
Notes (up) ; This work was supported by the Flemish Science Foundation (Fonds Wetenschappelijk Onderzoek – FWO) and the Methusalem program of the Flemish government. One of us (L. C.) receives support as a postdoctoral fellow of the FWO. ; Approved Most recent IF: 3.836; 2014 IF: 3.736
Call Number UA @ lucian @ c:irua:122204 Serial 2355
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Author Neek-Amal, M.; Covaci, L.; Peeters, F.M.
Title Nanoengineered nonuniform strain in graphene using nanopillars Type A1 Journal article
Year 2012 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 86 Issue 4 Pages 041405
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Recent experiments showed that nonuniform strain can be produced by depositing graphene over pillars. We employed atomistic calculations to study the nonuniform strain and the induced pseudomagnetic field in graphene on top of nanopillars. By decreasing the distance between the nanopillars a complex distribution for the pseudomagnetic field can be generated. Furthermore, we performed tight-binding calculations of the local density of states (LDOS) by using the relaxed graphene configuration obtained from atomistic calculations. We find that the quasiparticle LDOS are strongly modified near the pillars, both at low energies showing sublattice polarization and at high energies showing shifts of the van Hove singularity. Our study shows that changing the specific pattern of the nanopillars allows us to create a desired shape of the pseudomagnetic field profile while the LDOS maps provide an input for experimental verification by scanning tunneling microscopy.
Address
Corporate Author Thesis
Publisher Place of Publication Lancaster, Pa Editor
Language Wos 000306313900001 Publication Date 2012-07-14
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 51 Open Access
Notes (up) ; This work was supported by the Flemish Science Foundation (FWO-V1) and the EuroGRAPHENE project CONGRAN. ; Approved Most recent IF: 3.836; 2012 IF: 3.767
Call Number UA @ lucian @ c:irua:100765 Serial 2255
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Author Esfahani, D.N.; Covaci, L.; Peeters, F.M.
Title Field effect on surface states in a doped Mott-insulator thin film Type A1 Journal article
Year 2013 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 87 Issue 3 Pages 035131-35136
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Surface effects of a doped thin film made of a strongly correlated material are investigated both in the absence and presence of a perpendicular electric field. We use an inhomogeneous Gutzwiller approximation for a single-band Hubbard model in order to describe correlation effects. For low doping, the bulk value of the quasiparticle weight is recovered exponentially deep into the slab, but with increasing doping, additional Friedel oscillations appear near the surface. We show that the inverse correlation length has a power-law dependence on the doping level. In the presence of an electrical field, considerable changes in the quasiparticle weight can be realized throughout the system. We observe a large difference (as large as five orders of magnitude) in the quasiparticle weight near the opposite sides of the slab. This effect can be significant in switching devices that use the surface states for transport. DOI: 10.1103/PhysRevB.87.035131
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000313941000001 Publication Date 2013-01-29
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 4 Open Access
Notes (up) ; This work was supported by the Flemish Science Foundation (FWO-VI). ; Approved Most recent IF: 3.836; 2013 IF: 3.664
Call Number UA @ lucian @ c:irua:110086 Serial 1190
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Author Muñoz, W.A.; Covaci, L.; Peeters, F.M.
Title Tight-binding study of bilayer graphene Josephson junctions Type A1 Journal article
Year 2012 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 86 Issue 18 Pages 184505-184507
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Using highly efficient simulations of the tight-binding Bogoliubov-de-Gennes model, we solved self-consistently for the pair correlation and the Josephson current in a superconducting-bilayer graphene-superconducting Josephson junction. Different doping levels for the non-superconducting link are considered in the short- and long-junction regimes. Self-consistent results for the pair correlation and superconducting current resemble those reported previously for single-layer graphene except at the Dirac point, where remarkable differences in the proximity effect are found, as well as a suppression of the superconducting current in the long-junction regime. Inversion symmetry is broken by considering a potential difference between the layers and we found that the supercurrent can be switched if the junction length is larger than the Fermi length.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000310840400005 Publication Date 2012-11-07
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 13 Open Access
Notes (up) ; This work was supported by the Flemish Science Foundation (FWO-VI). ; Approved Most recent IF: 3.836; 2012 IF: 3.767
Call Number UA @ lucian @ c:irua:105149 Serial 3661
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Author Covaci, L.; Peeters, F.M.
Title Superconducting proximity effect in graphene under inhomogeneous strain Type A1 Journal article
Year 2011 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 84 Issue 24 Pages 241401-241401,4
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The interplay between quantum Hall states and Cooper pairs is usually hindered by the suppression of the superconducting state due to the strong magnetic fields needed to observe the quantum Hall effect. From this point of view, graphene is special since it allows the creation of strong pseudomagnetic fields due to strain. We show that in a Josephson junction made of strained graphene, Cooper pairs will diffuse into the strained region. The pair correlation function will be sublattice polarized due to the polarization of the local density of states in the zero pseudo-Landau level. We uncover two regimes: (1) one in which the cyclotron radius is larger than the junction length, in which case the supercurrent will be enhanced, and (2) the long junction regime where the supercurrent is strongly suppressed because the junction becomes an insulator. In the latter case quantized Hall states form and Andreev scattering at the normal/superconducting interface will induce edge states. Our numerical calculation has become possible due to an extension of the Chebyshev-Bogoliubovde Gennes method to computations on video cards (GPUs).
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000297766600003 Publication Date 2011-12-06
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 27 Open Access
Notes (up) ; This work was supported by the Flemish Science Foundation (FWO-Vl) and the Euro GRAPHENE project CONGRAN. Discussions with Andrey Chaves are gratefully acknowledged. ; Approved Most recent IF: 3.836; 2011 IF: 3.691
Call Number UA @ lucian @ c:irua:93962 Serial 3364
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Author Muñoz, W.A.; Covaci, L.; Peeters, F.M.
Title Tight-binding description of intrinsic superconducting correlations in multilayer graphene Type A1 Journal article
Year 2013 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 87 Issue 13 Pages 134509-7
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Using highly efficient GPU-based simulations of the tight-binding Bogoliubov-de Gennes equations we solve self-consistently for the pair correlation in rhombohedral (ABC) and Bernal (ABA) multilayer graphene by considering a finite intrinsic s-wave pairing potential. We find that the two different stacking configurations have opposite bulk/surface behavior for the order parameter. Surface superconductivity is robust for ABC stacked multilayer graphene even at very low pairing potentials for which the bulk order parameter vanishes, in agreement with a recent analytical approach. In contrast, for Bernal stacked multilayer graphene, we find that the order parameter is always suppressed at the surface and that there exists a critical value for the pairing potential below which no superconducting order is achieved. We considered different doping scenarios and find that homogeneous doping strongly suppresses surface superconductivity while nonhomogeneous field-induced doping has a much weaker effect on the superconducting order parameter. For multilayer structures with hybrid stacking (ABC and ABA) we find that when the thickness of each region is small (few layers), high-temperature surface superconductivity survives throughout the bulk due to the proximity effect between ABC/ABA interfaces where the order parameter is enhanced. DOI: 10.1103/PhysRevB.87.134509
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000317390000006 Publication Date 2013-04-11
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 37 Open Access
Notes (up) ; This work was supported by the Flemish Science Foundation (FWO-Vl) and the Methusalem funding of the Flemish Government. ; Approved Most recent IF: 3.836; 2013 IF: 3.664
Call Number UA @ lucian @ c:irua:108469 Serial 3660
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Author Nasr Esfahani, D.; Covaci, L.; Peeters, F.M.
Title Surface correlation effects in two-band strongly correlated slabs Type A1 Journal article
Year 2014 Publication Journal of physics : condensed matter Abbreviated Journal J Phys-Condens Mat
Volume 26 Issue 7 Pages 075601-75609
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Using an extension of the Gutzwiller approximation for an inhomogeneous system, we study the two-band Hubbard model with unequal band widths for a slab geometry. The aim is to investigate the mutual effect of individual bands on the spatial distribution of quasi-particle weight and charge density, especially near the surface of the slab. The main effect of the difference in band width is the presence of two different length scales corresponding to the quasi-particle profile of each band. This is enhanced in the vicinity of the critical interaction of the narrow band where an orbitally selective Mott transition occurs and a surface dead layer forms for the narrow band. For the doped case, two different regimes of charge transfer between the surface and the bulk of the slab are revealed. The charge transfer from surface/ center to center/ surface depends on both the doping level and the average relative charge accumulated in each band. Such effects could also be of importance when describing the accumulation of charges at the interface between structures made of multi-band strongly correlated materials.
Address
Corporate Author Thesis
Publisher Place of Publication London Editor
Language Wos 000330719500009 Publication Date 2014-01-29
Series Editor Series Title Abbreviated Series Title
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 1 Open Access
Notes (up) ; This work was supported by the Flemish Science Foundation (FWO-Vl) and the Methusalem program of the Flemish government. One of us (LC) is a postdoctoral fellow of the FWO-Vl. ; Approved Most recent IF: 2.649; 2014 IF: 2.346
Call Number UA @ lucian @ c:irua:115723 Serial 3395
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Author Zha, G.-Q.; Covaci, L.; Zhou, S.-P.; Peeters, F.M.
Title Proximity-induced pseudogap in mesoscopic superconductor/normal-metal bilayers Type A1 Journal article
Year 2010 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 82 Issue 14 Pages 140502-140502,4
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Recent scanning tunneling microscopy (STM) measurements of the proximity effect in Au/La2−xSrxCuO4 and La1.55Sr0.45CuO4/La2−xSrxCuO4 bilayers showed a proximity-induced pseudogap [O. Yuli, I. Asulin, Y. Kalcheim, G. Koren, and O. Millo, Phys. Rev. Lett. 103, 197003 (2009)]. We describe the proximity effect in mesoscopic superconductor/normal-metal bilayers by using the Bogoliubov-de Gennes equations for a tight-binding Hamiltonian with competing antiferromagnetic and d-wave superconductivity orders. The temperature-dependent local density of states is calculated as a function of the distance from the interface. Bound state due to both d-wave and spin-density wave gaps are formed in the normal metal for energies less than the respective gaps. If there is a mismatch between the Fermi velocities in the two layers we observe that these states will shift in energy when spin-density wave order is present, thus inducing a minigap at finite energy. We conclude that the STM measurement in the proximity structures is able to distinguish between the two scenarios proposed for the pseudogap (competing or precursor to superconductivity).
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000282507200002 Publication Date 2010-10-05
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 7 Open Access
Notes (up) ; This work was supported by the Flemish Science Foundation (FWO-Vl), by Belgian Science Policy (IAP), by National Natural Science Foundation of China under Grants No. 10904089 and No. 60971053, by the Research Fund of Higher Education of China under Grant No. 20093108120005, by Shanghai Leading Academic Discipline project under Grant No. S30105, by Science and Technology Committee of Shanghai Municipal under Grant No. 09JC1406000, by Shanghai Municipal Education Committee under Grants No. shu-08053 and No. 10zz63, and by Innovation Funds of Shanghai University. ; Approved Most recent IF: 3.836; 2010 IF: 3.774
Call Number UA @ lucian @ c:irua:85028 Serial 2735
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Author Covaci, L.; Peeters, F.M.; Berciu, M.
Title Efficient numerical approach to inhomogeneous superconductivity: the Chebyshev-Bogoliubov-de Gennes method Type A1 Journal article
Year 2010 Publication Physical review letters Abbreviated Journal Phys Rev Lett
Volume 105 Issue 16 Pages 167006,1-167006,4
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract We propose a highly efficient numerical method to describe inhomogeneous superconductivity by using the kernel polynomial method in order to calculate the Greens functions of a superconductor. Broken translational invariance of any type (impurities, surfaces, or magnetic fields) can be easily incorporated. We show that limitations due to system size can be easily circumvented and therefore this method opens the way for the study of scenarios and/or geometries that were unaccessible before. The proposed method is highly efficient and amenable to large scale parallel computation. Although we only use it in the context of superconductivity, it is applicable to other inhomogeneous mean-field theories.
Address
Corporate Author Thesis
Publisher Place of Publication New York, N.Y. Editor
Language Wos 000282816300018 Publication Date 2010-10-12
Series Editor Series Title Abbreviated Series Title
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 80 Open Access
Notes (up) ; This work was supported by the Flemish Science Foundation (FWO-Vl), CIfAR, and NSERC. Discussions with Frank Marsiglio are gratefully acknowledged. ; Approved Most recent IF: 8.462; 2010 IF: 7.622
Call Number UA @ lucian @ c:irua:84899 Serial 875
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Author Berdiyorov, G.R.; de Romaguera, A.R.C.; Milošević, M.V.; Doria, M.M.; Covaci, L.; Peeters, F.M.
Title Dynamic and static phases of vortices under an applied drive in a superconducting stripe with an array of weak links Type A1 Journal article
Year 2012 Publication European physical journal : B : condensed matter and complex systems Abbreviated Journal Eur Phys J B
Volume 85 Issue 4 Pages 130-130,8
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Static and dynamic properties of superconducting vortices in a superconducting stripe with a periodic array of weakly-superconducting (or normal metal) regions are studied in the presence of external magnetic and electric fields. The time-dependent Ginzburg-Landau theory is used to describe the electronic transport, where the anisotropy is included through the spatially-dependent critical temperature T-c. Superconducting vortices penetrating into the weak-superconducting region with smaller T-c are more mobile than the ones in the strong superconducting regions. We observe periodic entrance and exit of vortices which reside in the weak link for some short interval. The mobility of the weakly-pinned vortices can be reduced by increasing the uniform applied magnetic field leading to distinct features in the voltage vs. magnetic field response of the system.
Address
Corporate Author Thesis
Publisher Place of Publication Berlin Editor
Language Wos 000303545400013 Publication Date 2012-04-20
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1434-6028;1434-6036; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 1.461 Times cited 32 Open Access
Notes (up) ; This work was supported by the Flemish Science Foundation (FWO-Vl), the Belgian Science Policy (IAP), the bilateral programme between Flanders and Brazil. G.R.B. and L.C. acknowledge individual support from FWO-Vl. A.R.de C.R. acknowledges CNPq and FACEPE for financial support. ; Approved Most recent IF: 1.461; 2012 IF: 1.282
Call Number UA @ lucian @ c:irua:98267 Serial 761
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Author Zhang, L.-F.; Covaci, L.; Milošević, M.V.; Berdiyorov, G.R.; Peeters, F.M.
Title Vortex states in nanoscale superconducting squares : the influence of quantum confinement Type A1 Journal article
Year 2013 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 88 Issue 14 Pages 144501
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Bogoliubov-de Gennes theory is used to investigate the effect of the size of a superconducting square on the vortex states in the quantum confinement regime. When the superconducting coherence length is comparable to the Fermi wavelength, the shape resonances of the superconducting order parameter have strong influence on the vortex configuration. Several unconventional vortex states, including asymmetric ones, giant-multivortex combinations, and states comprising giant antivortices, were found as ground states and their stability was found to be very sensitive on the value of k(F)xi(0), the size of the sample W, and the magnetic flux Phi. By increasing the temperature and/or enlarging the size of the sample, quantum confinement is suppressed and the conventional mesoscopic vortex states as predicted by the Ginzburg-Laudau (GL) theory are recovered. However, contrary to the GL results we found that the states containing symmetry-induced vortex-antivortex pairs are stable over the whole temperature range. It turns out that the inhomogeneous order parameter induced by quantum confinement favors vortex-antivortex molecules, as well as giant vortices with a rich structure in the vortex core-unattainable in the GL domain.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000325498300004 Publication Date 2013-10-09
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 19 Open Access
Notes (up) ; This work was supported by the Flemish Science Foundation (FWO-Vlaanderen) and Methusalem Funding of the Flemish government. ; Approved Most recent IF: 3.836; 2013 IF: 3.664
Call Number UA @ lucian @ c:irua:111145 Serial 3891
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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
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000300240100002 Publication Date 2012-02-14
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 3 Open Access
Notes (up) ; 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
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Author Berdiyorov, G.R.; Milošević, M.V.; Covaci, L.; Peeters, F.M.
Title Rectification by an imprinted phase in a Josephson junction Type A1 Journal article
Year 2011 Publication Physical review letters Abbreviated Journal Phys Rev Lett
Volume 107 Issue 17 Pages 177008-177008,5
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract A Josephson phase shift can be induced in a Josephson junction by a strategically nearby pinned Abrikosov vortex (AV). For an asymmetric distribution of an imprinted phase along the junction (controlled by the position of the AV) such a simple system is capable of rectification of ac current in a broad and tunable frequency range. The resulting rectified voltage is a consequence of the directed motion of a Josephson antivortex which forms a pair with the AV when at local equilibrium. The proposed realization of the ratchet potential by an imprinted phase is more efficient than the asymmetric geometry of the junction itself, is easily realizable experimentally, and provides rectification even in the absence of an applied magnetic field.
Address
Corporate Author Thesis
Publisher Place of Publication New York, N.Y. Editor
Language Wos 000296985000008 Publication Date 2011-10-21
Series Editor Series Title Abbreviated Series Title
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 28 Open Access
Notes (up) ; This work was supported by the Flemish Science Foundation (FWO-Vlaanderen) and the Belgian Science Policy (IAP). G. R. B. and L. C. acknowledge individual support from FWO-Vlaanderen. ; Approved Most recent IF: 8.462; 2011 IF: 7.370
Call Number UA @ lucian @ c:irua:93715 Serial 2847
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Author Zhang, L.-F.; Covaci, L.; Peeters, F.M.
Title Tomasch effect in nanoscale superconductors Type A1 Journal article
Year 2015 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 91 Issue 91 Pages 024508
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The Tomasch effect (TE) is due to quasiparticle interference (QPI) as induced by a nonuniform superconducting order parameter, which results in oscillations in the density of states (DOS) at energies above the superconducting gap. Quantum confinement in nanoscale superconductors leads to an inhomogenerous distribution of the Cooperpair condensate, which, as we found, triggers the manifestation of a new TE. We investigate the electronic structure of nanoscale superconductors by solving the Bogoliubov-de Gennes (BdG) equations self-consistently and describe the TE determined by two types of processes, involving two-or three-subband QPIs. Both types of QPIs result in additional BCS-like Bogoliubov-quasiparticles and BCS-like energy gaps leading to oscillations in the DOS and modulated wave patterns in the local density of states. These effects are strongly related to the symmetries of the system. A reduced 4 x 4 inter-subband BdG Hamiltonian is established in order to describe analytically the TE of two-subband QPIs. Our study is relevant to nanoscale superconductors, either nanowires or thin films, Bose-Einsten condensates, and confined systems such as two-dimensional electron gas interface superconductivity.
Address
Corporate Author Thesis
Publisher Place of Publication Lancaster, Pa Editor
Language Wos 000348473700003 Publication Date 2015-01-16
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 6 Open Access
Notes (up) ; This work was supported by the Flemish Science Foundation (FWO-Vlaanderen) and the Methusalem funding of the Flemish Government. ; Approved Most recent IF: 3.836; 2015 IF: 3.736
Call Number c:irua:123864 Serial 3670
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Author Zhang, L.-F.; Covaci, L.; Peeters, F.M.
Title Position-dependent effect of non-magnetic impurities on superconducting properties of nanowires Type A1 Journal article
Year 2015 Publication Europhysics letters Abbreviated Journal Epl-Europhys Lett
Volume 109 Issue 109 Pages 17010
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Anderson's theorem states that non-magnetic impurities do not change the bulk properties of conventional superconductors. However, as the dimensionality is reduced, the effect of impurities becomes more significant. Here we investigate superconducting nanowires with diameter comparable to the Fermi wavelength $\lambda_F$ (which is less than the superconducting coherence length) by using a microscopic description based on the Bogoliubov-de Gennes method. We find that: 1) impurities strongly affect the superconducting properties, 2) the effect is impurity position dependent, and 3) it exhibits opposite behavior for resonant and off-resonant wire widths. We show that this is due to the interplay between the shape resonances of the order parameter and the subband energy spectrum induced by the lateral quantum confinement. These effects can be used to manipulate the Josephson current, filter electrons by subband and investigate the symmetries of the superconducting subband gaps.
Address
Corporate Author Thesis
Publisher Place of Publication Paris Editor
Language Wos 000348592100029 Publication Date 2015-01-21
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0295-5075 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 1.957 Times cited 7 Open Access
Notes (up) ; This work was supported by the Flemish Science Foundation (FWO-Vlaanderen) and the Methusalem funding of the Flemish Government. ; Approved Most recent IF: 1.957; 2015 IF: 2.095
Call Number UA @ lucian @ c:irua:128424 Serial 4227
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Author Zhang, L.-F.; Covaci, L.; Milošević, M.V.; Berdiyorov, G.R.; Peeters, F.M.
Title Unconventional vortex states in nanoscale superconductors due to shape-induced resonances in the inhomogeneous Cooper-pair condensate Type A1 Journal article
Year 2012 Publication Physical review letters Abbreviated Journal Phys Rev Lett
Volume 109 Issue 10 Pages 107001
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Vortex matter in mesoscopic superconductors is known to be strongly affected by the geometry of the sample. Here we show that in nanoscale superconductors with coherence length comparable to the Fermi wavelength the shape resonances of the order parameter results in an additional contribution to the quantum topological confinement-leading to unconventional vortex configurations. Our Bogoliubov-de Gennes calculations in a square geometry reveal a plethora of asymmetric, giant multivortex, and vortex-antivortex structures, stable over a wide range of parameters and which are very different from those predicted by the Ginzburg-Landau theory. These unconventional states are relevant for high-T-c nanograins, confined Bose-Einstein condensates, and graphene flakes with proximity-induced superconductivity.
Address
Corporate Author Thesis
Publisher Place of Publication New York, N.Y. Editor
Language Wos 000308295700014 Publication Date 2012-09-05
Series Editor Series Title Abbreviated Series Title
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 31 Open Access
Notes (up) ; This work was supported by the Flemish Science Foundation (FWO-Vlaanderen). ; Approved Most recent IF: 8.462; 2012 IF: 7.943
Call Number UA @ lucian @ c:irua:101850 Serial 3801
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Author Zhang, L.; Fernández Becerra, V.; Covaci, L.; Milošević, M.V.
Title Electronic properties of emergent topological defects in chiral p-wave superconductivity Type A1 Journal article
Year 2016 Publication Physical review B Abbreviated Journal Phys Rev B
Volume 94 Issue 94 Pages 024520
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Chiral p-wave superconductors in applied magnetic field can exhibit more complex topological defects than just conventional superconducting vortices, due to the two-component order parameter (OP) and the broken time-reversal symmetry. We investigate the electronic properties of those exotic states, some of which contain clusters of one-component vortices in chiral components of the OP and/or exhibit skyrmionic character in the relative OP space, all obtained as a self-consistent solution of the microscopic Bogoliubov-de Gennes equations. We reveal the link between the local density of states (LDOS) of the novel topological states and the behavior of the chiral domain wall between the OP components, enabling direct identification of those states in scanning tunneling microscopy. For example, a skyrmion always contains a closed chiral domain wall, which is found to be mapped exactly by zero-bias peaks in LDOS. Moreover, the LDOS exhibits electron-hole asymmetry, which is different from the LDOS of conventional vortex states with same vorticity. Finally, we present the magnetic field and temperature dependence of the properties of a skyrmion, indicating that this topological defect can be surprisingly large in size, and can be pinned by an artificially indented nonsuperconducting closed path in the sample. These features are expected to facilitate the experimental observation of skyrmionic states, thereby enabling experimental verification of chirality in emerging superconducting materials.
Address
Corporate Author Thesis
Publisher American Physical Society Place of Publication New York, N.Y Editor
Language Wos 000381479500002 Publication Date 2016-07-26
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2469-9969 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 3.836 Times cited 27 Open Access
Notes (up) ; This work was supported by the Fonds Wetenschappelijk Onderzoek (FWO). ; Approved Most recent IF: 3.836
Call Number UA @ lucian @ c:irua:135742 Serial 4303
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Author Zha, G.-Q.; Covaci, L.; Peeters, F.M.; Zhou, S.-P.
Title Mixed pairing symmetries and flux-induced spin current in mesoscopic superconducting loops with spin correlations Type A1 Journal article
Year 2015 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 91 Issue 91 Pages 214504
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract We numerically investigate the mixed pairing symmetries inmesoscopic superconducting loops in the presence of spin correlations by solving the Bogoliubov-de Gennes equations self-consistently. The spatial variations of the superconducting order parameters and the spontaneous magnetization are determined by the band structure. When the threaded magnetic flux turns on, the charge and spin currents both emerge and depict periodic evolution. In the case of a mesoscopic loop with dominant triplet p(x) +/- ip(y)-wave symmetry, a slight change of the chemical potential may lead to novel flux-dependent evolution patterns of the ground-state energy and the magnetization. The spin-polarized currents show pronounced quantum oscillations with fractional periods due to the appearance of energy jumps in flux, accompanied with a steplike feature of the enhanced spin current. Particularly, at some appropriate flux, the peaks of the zero-energy local density of states clearly indicate the occurrence of the odd-frequency pairing. In the case of a superconducting loop with dominant singlet d(x2-y2)-wave symmetry, the spatial profiles of the zero-energy local density of states and the magnetization show spin-dependent features on different sample diagonals. Moreover, the evolution of the flux-induced spin current always exhibits an hc/e periodicity.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000355647100003 Publication Date 2015-06-05
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 15 Open Access
Notes (up) ; This work was supported by the National Natural Science Foundation of China under Grants No. 61371020 and No. 61271163, by the Visiting Scholar Program of Shanghai Municipal Education Commission, and by the Flemish Science Foundation (FWO-Vl). ; Approved Most recent IF: 3.836; 2015 IF: 3.736
Call Number c:irua:126433 Serial 2089
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Author Zhang, L.-F.; Covaci, L.; Milošević, M.V.
Title Topological phase transitions in small mesoscopic chiral p-wave superconductors Type A1 Journal article
Year 2017 Publication Physical review B Abbreviated Journal Phys Rev B
Volume 96 Issue 22 Pages 224512
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract <script type='text/javascript'>document.write(unpmarked('Spin-triplet chiral p-wave superconductivity is typically described by a two-component order parameter, and as such is prone to unique emergent effects when compared to the standard single-component superconductors. Here we present the equilibrium phase diagram for small mesoscopic chiral p-wave superconducting disks in the presence of magnetic field, obtained by solving the microscopic Bogoliubov-de Gennes equations self-consistently. In the ultrasmall limit, the cylindrically symmetric giant-vortex states form the ground state of the system. However, with increasing sample size, the cylindrical symmetry is broken as the two components of the order parameter segregate into domains, and the number of fragmented domain walls between them characterizes the resulting states. Such domain walls are topological defects unique for the p-wave order, and constitute a dominant phase in the mesoscopic regime. Moreover, we find two possible types of domain walls, identified by their chirality-dependent interaction with the edge states.'));
Address
Corporate Author Thesis
Publisher American Physical Society Place of Publication New York, N.Y Editor
Language Wos 000418653500012 Publication Date 2017-12-26
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 3.836 Times cited 18 Open Access
Notes (up) ; This work was supported by the Research Foundation Flanders (FWO-Vlaanderen) and the Special Research Funds of the University of Antwerp. ; Approved Most recent IF: 3.836
Call Number UA @ lucian @ c:irua:148504 Serial 4901
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Author Zhang, L.-F.; Flammia, L.; Covaci, L.; Perali, A.; Milošević, M.V.
Title Multifaceted impact of a surface step on superconductivity in atomically thin films Type A1 Journal article
Year 2017 Publication Physical review B Abbreviated Journal Phys Rev B
Volume 96 Issue 10 Pages 104509
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Recent experiments show that an atomic step on the surface of atomically thin metallic films can strongly affect electronic transport. Here we reveal multiple and versatile effects that such a surface step can have on superconductivity in ultrathin films. By solving the Bogoliubov-de Gennes equations self-consistently in this regime, where quantum confinement dominates the emergent physics, we show that the electronic structure is profoundly modified on the two sides of the step, as is the spatial distribution of the superconducting order parameter and its dependence on temperature and electronic gating. Furthermore, the surface step changes nontrivially the transport properties both in the proximity-induced superconducting pair correlations and the Josephson effect, depending on the step height. These results offer a new route to tailor superconducting circuits and design atomically thin heterojunctions made of one same material.
Address
Corporate Author Thesis
Publisher American Physical Society Place of Publication New York, N.Y Editor
Language Wos 000411076000012 Publication Date 2017-09-18
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 3.836 Times cited 7 Open Access
Notes (up) ; This work was supported by the Research Foundation Flanders (FWO-Vlaanderen), the Special Research Funds of the University of Antwerp (TOPBOF project) and the Italian MIUR through the PRIN 2015 program (Contract No. 2015C5SEJJ001). ; Approved Most recent IF: 3.836
Call Number UA @ lucian @ c:irua:146750 Serial 4790
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Author Flammia, L.; Zhang, L.-F.; Covaci, L.; Perali, A.; Milošević, M.V.
Title Superconducting nanoribbon with a constriction : a quantum-confined Josephson junction Type A1 Journal article
Year 2018 Publication Physical review B Abbreviated Journal Phys Rev B
Volume 97 Issue 13 Pages 134514
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Extended defects are known to strongly affect nanoscale superconductors. Here, we report the properties of superconducting nanoribbons with a constriction formed between two adjacent step edges by solving the Bogoliubov-de Gennes equations self-consistently in the regime where quantum confinement is important. Since the quantum resonances of the superconducting gap in the constricted area are different from the rest of the nanoribbon, such constriction forms a quantum-confined S-S'-S Josephson junction, with a broadly tunable performance depending on the length and width of the constriction with respect to the nanoribbon, and possible gating. These findings provide an intriguing approach to further tailor superconducting quantum devices where Josephson effect is of use.
Address
Corporate Author Thesis
Publisher American Physical Society Place of Publication New York, N.Y Editor
Language Wos 000430161500004 Publication Date 2018-04-17
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; WoS citing articles
Impact Factor 3.836 Times cited 7 Open Access
Notes (up) ; This work was supported by the Research Foundation Flanders (FWO-Vlaanderen), the Special Research Funds of the University of Antwerp (TOPBOF), the Italian MIUR through the PRIN 2015 program (Contract No. 2015C5SEJJ001), the MultiSuper network, and the EU-COST NANOCOHYBRI action CA16218. ; Approved Most recent IF: 3.836
Call Number UA @ lucian @ c:irua:150754UA @ admin @ c:irua:150754 Serial 4980
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Author Li, Z.; Covaci, L.; Berciu, M.; Baillie, D.; Marsiglio, F.
Title Impact of spin-orbit coupling on the Holstein polaron Type A1 Journal article
Year 2011 Publication Physical review : B : condensed matter and materials physics Abbreviated Journal Phys Rev B
Volume 83 Issue 19 Pages 195104-195104,9
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 a Rashba-like spin-orbit interaction. Our results corroborate previous work performed with the momentum average approximation and with weak-coupling perturbation theory. We find that spin-orbit coupling increases the effective mass in the regime with weak electron-phonon coupling, and decreases the effective mass in the regimes of intermediate and strong electron-phonon coupling. Analytical strong-coupling perturbation theory results confirm our numerical results in the small-polaron regime. A large amount of spin-orbit coupling can lead to a significant lowering of the polaron effective mass.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000290162500001 Publication Date 2011-05-03
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 9 Open Access
Notes (up) ; This work was supported in part by the Natural Sciences and Engineering Research Council of Canada (NSERC), by ICORE (Alberta), by Alberta Ingenuity, by the Flemish Science Foundation (FWO-Vl), and by the Canadian Institute for Advanced Research (CIfAR). ; Approved Most recent IF: 3.836; 2011 IF: 3.691
Call Number UA @ lucian @ c:irua:89718 Serial 1561
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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
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000303794900003 Publication Date 2012-05-09
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 18 Open Access
Notes (up) ; 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
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Author Garcia, J.H.; Covaci, L.; Rappoport, T.G.
Title Real-space calculation of the conductivity tensor for disordered topological matter Type A1 Journal article
Year 2015 Publication Physical review letters Abbreviated Journal Phys Rev Lett
Volume 114 Issue 114 Pages 116602
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract We describe an efficient numerical approach to calculate the longitudinal and transverse Kubo conductivities of large systems using Bastin's formulation. We expand the Green's functions in terms of Chebyshev polynomials and compute the conductivity tensor for any temperature and chemical potential in a single step. To illustrate the power and generality of the approach, we calculate the conductivity tensor for the quantum Hall effect in disordered graphene and analyze the effect of the disorder in a Chern insulator in Haldane's model on a honeycomb lattice.
Address
Corporate Author Thesis
Publisher Place of Publication New York, N.Y. Editor
Language Wos 000351430600010 Publication Date 2015-03-20
Series Editor Series Title Abbreviated Series Title
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 69 Open Access
Notes (up) ; We acknowledge A. R. Hernandez, A. Ferreira, and E. Mucciolo for discussions. T. G. R and J. H. G acknowledge the Brazilian agencies CNPq, FAPERJ, and INCT de Nanoestruturas de Carbono for financial support. L. C. acknowledges the Flemish Science Foundation (FWO-Vlaanderen) for financial support. ; Approved Most recent IF: 8.462; 2015 IF: 7.512
Call Number c:irua:125467 Serial 2827
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