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SUMMARY:Do epitaxial semiconductor-superconductor hybrid devices really su
 pport topological superconductivity?
DTSTART:20181107T090000Z
DTEND:20181107T100000Z
DTSTAMP:20260514T112800Z
UID:indico-event-6648@indico.fysik.su.se
DESCRIPTION:Speakers: Chris Reeg (Uni Basel)\n\nAbstract: In recent years 
 there has been significant emphasis placed on the development of hybrid de
 vices consisting of a semiconducting nanowire coupled to a thin layer of e
 pitaxially grown superconducting aluminum\, and these devices are widely r
 egarded as the ideal platform for studying topological superconductivity d
 ue to the very strong and uniform contact between the two materials. In th
 is talk\, I will discuss a microscopic treatment of the proximity effect i
 n such a device and show that this approach exhibits significant deviation
 s from more frequently utilized phenomenological theories. Most importantl
 y\, the finite thickness of the superconducting film introduces a large en
 ergy scale to the system that is determined by the quantized subband spaci
 ng. In the limit where a sizable superconducting gap is induced in the sem
 iconductor\, we show that all material parameters of the semiconductor bec
 ome significantly renormalized due to hybridization with the superconducto
 r and that the semiconducting bands undergo a large effective chemical pot
 ential shift that is comparable to the large subband spacing of the superc
 onductor. In this limit\, we argue it is unlikely that the hybrid system c
 an support topological superconductivity. Additionally\, in order to expla
 in numerous recent experimental observations of zero-bias conductance peak
 s in these epitaxial devices\, we present an analytical theory describing 
 how one might generically observe topologically trivial zero-energy Andree
 v bound states in such a device.\n\nhttps://indico.fysik.su.se/event/6648/
LOCATION:NOrdita South Seminar room (Nordita South/Cond Mat)
URL:https://indico.fysik.su.se/event/6648/
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