Effective g-factor in Majorana Wires

TL;DR

This paper investigates how the effective g-factor in hybrid InAs nanowires with Al shells varies with carrier density and its implications for Majorana devices, revealing a step-like reduction and gap behavior.

Contribution

It introduces measurements of the effective g-factor in hybrid nanowires and links it to the superconducting density of states distribution and Majorana device requirements.

Findings

g* decreases step-like with reduced carrier density

Hard gap improves as carrier density decreases

Gap closing and reopening observed with zero-bias peak emergence

Abstract

We use the effective g-factor of subgap states, g*, in hybrid InAs nanowires with an epitaxial Al shell to investigate how the superconducting density of states is distributed between the semiconductor core and the metallic shell. We find a step-like reduction of g* and improved hard gap with reduced carrier density in the nanowire, controlled by gate voltage. These observations are relevant for Majorana devices, which require tunable carrier density and g* exceeding the g-factor of the proximitizing superconductor. Additionally, we observe the closing and reopening of a gap in the subgap spectrum coincident with the appearance of a zero-bias conductance peak.