Andreev spectrum and supercurrents in nanowire-based SNS junctions containing Majorana bound states
Entidad
UAM. Departamento de Física de la Materia CondensadaEditor
Beilstein - Institut zur Foerderung der Chemischen WissenschaftenFecha de edición
2018-05-01Cita
10.3762/bjnano.9.127
Beilstein Journal of Nanotechnology 9.1 (2018): 1339-1357
ISSN
2190-4286DOI
10.3762/bjnano.9.127Financiado por
J.C. thanks O. A. Awoga, K. Björnson, M. Benito and S. Pradhan for motivating and helpful discussions. J.C. and A.B.S. acknowledge financial support from the Swedish Research Council (Vetenskapsrådet), the Göran Gustafsson Foundation, the Swedish Foundation for Strategic Research (SSF), and the Knut and Alice Wallenberg Foundation through the Wallenberg Academy Fellows program. We also acknowledge financial support from the Spanish Ministry of Economy and Competitiveness through Grant No. FIS2015-64654-P (R. A.), FIS2016-80434-P (AEI/FEDER, EU) (E. P.) and the Ramón y Cajal programme through grant No. RYC-2011-09345 (E. P)Proyecto
Gobierno de España. FIS2015-64654-P; Gobierno de España. FIS2016-80434-PVersión del editor
https://doi.org/10.3762/bjnano.9.127Materias
Hybrid superconductor-semiconductor nanowire-superconductor junctions; Josephson effect; Majorana bound states; Nanowires; Spin-orbit coupling; Zeeman interaction; FísicaResumen
Hybrid superconductor-semiconductor nanowires with Rashba spin-orbit coupling are arguably becoming the leading platform for the search of Majorana bound states (MBSs) in engineered topological superconductors. We perform a systematic numerical study of the low-energy Andreev spectrum and supercurrents in short and long superconductor-normal-superconductor junctions made of nanowires with strong Rashba spin-orbit coupling, where an external Zeeman field is applied perpendicular to the spin-orbit axis. In particular, we investigate the detailed evolution of the Andreev bound states from the trivial into the topological phase and their relation with the emergence of MBSs. Due to the finite length, the system hosts four MBSs, two at the inner part of the junction and two at the outer one. They hybridize and give rise to a finite energy splitting at a superconducting phase difference of p, a wellvisible effect that can be traced back to the evolution of the energy spectrum with the Zeeman field: from the trivial phase with Andreev bound states into the topological phase with MBSs. Similarly, we carry out a detailed study of supercurrents for short and long junctions from the trivial to the topological phases. The supercurrent, calculated from the Andreev spectrum, is 2p-periodic in the trivial and topological phases. In the latter it exhibits a clear sawtooth profile at a phase difference of p when the energy splitting is negligible, signalling a strong dependence of current-phase curves on the length of the superconducting regions. Effects of temperature, scalar disorder and reduction of normal transmission on supercurrents are also discussed. Further, we identify the individual contribution of MBSs. In short junctions the MBSs determine the current-phase curves, while in long junctions the spectrum above the gap (quasi-continuum) introduces an important contribution
Lista de ficheros
Google Scholar:Cayao, Jorge
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Black-Schaffer, Annica M.
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Prada, Elsa
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Aguado, Ramón
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