SNS junctions in nanowires with spin-orbit coupling: Role of confinement and helicity on the subgap spectrum
Entity
UAM. Departamento de Física de la Materia CondensadaPublisher
American Physical SocietyDate
2015-01-29Citation
10.1103/PhysRevB.91.024514
Physical Review B - Condensed Matter and Materials Physics 91.2 (2015): 024514
ISSN
1098-0121 (print); 1550-235X (online)DOI
10.1103/PhysRevB.91.024514Funded by
We acknowledge the support of the European Research Council and the Spanish Ministry of Economy and Innovation through the JAE-Predoc Program, (J.C.) Grants No. FIS2011-23713 (P.S.-J), No. FIS2012-33521 (R.A.), No. FIS2013-47328 (E.P.), and the Ramón y Cajal Program (E.P)Project
Gobierno de España. FIS2011- 23713; Gobierno de España. FIS2012-33521; Gobierno de España. FIS2013- 47328Editor's Version
http://dx.doi.org/10.1103/PhysRevB.91.024514Subjects
SNS; Semiconducting nanowires; Ballistic junctions; Distinct subgap; FísicaRights
©2015 American Physical SocietyAbstract
We study normal transport and the subgap spectrum of superconductor-normal-superconductor (SNS) junctions made of semiconducting nanowires with strong Rashba spin-orbit coupling. We focus, in particular, on the role of confinement effects in long ballistic junctions. In the normal regime, scattering at the two contacts gives rise to two distinct features in conductance: Fabry-Perot resonances and Fano dips. The latter arise in the presence of a strong Zeeman field B that removes a spin sector in the leads (helical leads), but not in the central region. Conversely, a helical central region between nonhelical leads exhibits helical gaps of half-quantum conductance,
with superimposed helical Fabry-Perot oscillations. These normal features translate into distinct subgap states when the leads become superconducting. In particular, Fabry-Perot resonances within the helical gap become parity-protected zero-energy states (parity crossings), well belowthe critical field Bc at which the superconducting
leads become topological. As a function of Zeeman field or Fermi energy, these zero modes oscillate around zero energy, forming characteristic loops, which evolve continuously into Majorana bound states as B exceeds Bc. The relation with the physics of parity crossings of Yu-Shiba-Rusinov bound states is discussed
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Google Scholar:Cayao, Jorge
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Prada, Elsa
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San-Jose, Pablo
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Aguado, Ramón
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