Majorana Fermions Under Uniaxial Stress in Semiconductor-Superconductor Heterostructures

TL;DR

This paper proposes using uniaxial stress to tune the topological superconducting regime in semiconductor nanowires, facilitating the realization of Majorana fermions by overcoming chemical potential pinning issues.

Contribution

It introduces a method to realize tunable topological superconductivity in nanowires via uniaxial stress, offering a practical alternative to electrical gating.

Findings

Uniaxial stress can tune the chemical potential in n-type nanowires.

Stress enhances the topological minigap in p-type systems.

Required stress levels are achievable with current experimental techniques.

Abstract

Spin-orbit coupled semiconductor nanowires with Zeeman splitting in proximity contact with bulk $s$-wave superconductivity have recently been proposed as a promising platform for realizing Majorana fermions. However, in this setup the chemical potential of the nanowire is generally pinned by the Fermi surface of the superconductor. This makes the tuning of the chemical potential by external electrical gates, a crucial requirement for unambiguous detection of Majorana fermions, very challenging in experiments. Here we show that tunable topological superconducting regime supporting Majorana fermions can be realized in semiconductor nanowires using uniaxial stress. For n-type nanowires the uniaxial stress tunes the effective chemical potential, while for p-type systems the effective pairing may also be modified by stress, thus significantly enhancing the topological minigap. We show that the required stress, of the order of 0.1%, is within current experimental reach using conventional piezo crystals.