Inverse proximity effect in semiconductor Majorana nanowires

TL;DR

This paper investigates how the inverse proximity effect impacts superconductivity in semiconductor-superconductor hybrid nanowires, revealing conditions that influence Majorana device operation and superconducting state stability under magnetic fields.

Contribution

It introduces a detailed analysis of the inverse proximity effect in semiconductor nanowires, highlighting its role in superconductivity suppression and reentrant behavior relevant for Majorana-based quantum devices.

Findings

Superconductivity is suppressed at low magnetic fields due to paramagnetic effects.

Reentrant superconductivity occurs at high magnetic fields in the topologically nontrivial regime.

Suppression of homogeneous superconductivity near topological transition points fosters FFLO instability.

Abstract

We study the influence of the inverse proximity effect on the superconductivity nucleation in hybrid structures consisting of the semiconducting nanowires placed in contact with a thin superconducting film and discuss the resulting restrictions on the operation of Majorana-based devices. A strong paramagnetic effect for electrons entering the semiconductor together with spin-orbit coupling and van Hove singularities in the electronic density of states in the wire are responsible for the suppression of superconducting correlations in the low field domain and for the reentrant superconductivity at high magnetic fields in the topologically nontrivial regime. The growth of the critical temperature in the latter case continues up to the upper critical field destroying the pairing inside the superconducting film due to either orbital or paramagnetic mechanism. The suppression of the homogeneous superconducting state near the boundary between the topological and non-topological regimes provides the conditions favorable for the Fulde-Ferrel-Larkin-Ovchinnikov instability.