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Finite-size effects in a nanowire strongly coupled to a thin superconducting shell

Reeg, Christopher and Loss, Daniel and Klinovaja, Jelena. (2017) Finite-size effects in a nanowire strongly coupled to a thin superconducting shell. Physical Review B, 96 (12). p. 125426.

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Official URL: https://edoc.unibas.ch/60921/

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Abstract

We study the proximity effect in a one-dimensional nanowire strongly coupled to a finite superconductor with a characteristic size which is much shorter than its coherence length. Such geometries have become increasingly relevant in recent years in the experimental search for Majorana fermions with the development of thin epitaxial Al shells which form a very strong contact with either InAs or InSb nanowires. So far, however, no theoretical treatment of the proximity effect in these systems has accounted for the finite size of the superconducting film. We show that the finite-size effects become very detrimental when the level spacing of the superconductor greatly exceeds its energy gap. Without any fine tuning of the size of the superconductor (on the scale of the Fermi wavelength), the tunneling energy scale must be larger than the level spacing in order to reach the ``hard gap`` regime which is seen ubiquitously in the experiments. However, in this regime, the large tunneling energy scale induces a large shift in the effective chemical potential of the nanowire and pushes the topological phase transition to magnetic field strengths which exceed the critical field of Al.
Faculties and Departments:05 Faculty of Science > Departement Physik > Physik > Theoretical Nano/Quantum Physics (Klinovaja)
UniBasel Contributors:Klinovaja, Jelena
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:American Physical Society
ISSN:2469-9950
e-ISSN:2469-9969
Note:Publication type according to Uni Basel Research Database: Journal article
Language:English
Identification Number:
Last Modified:07 Mar 2018 14:30
Deposited On:07 Mar 2018 14:30

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