Zero-bias peaks in spin-orbit coupled superconducting wires with and without Majorana end-states

TL;DR

This paper investigates zero-bias peaks in spin-orbit coupled superconducting wires, demonstrating that such peaks can occur without Majorana end-states, especially under realistic disorder and temperature conditions, challenging their use as definitive Majorana signatures.

Contribution

The study shows that non-quantized zero-bias peaks can arise in trivial wires without Majorana states, emphasizing the need for additional criteria to confirm Majorana presence.

Findings

Zero-bias peaks can occur without Majorana states in trivial wires.

Disorder and temperature effects can produce non-quantized peaks.

Comparison with experiments highlights criteria for identifying Majorana states.

Abstract

One of the simplest proposed experimental probes of a Majorana bound-state is a quantized (2e^2/h) value of zero-bias tunneling conductance. When temperature is somewhat larger than the intrinsic width of the Majorana peak, conductance is no longer quantized, but a zero-bias peak can remain. Such a non-quantized zero-bias peak has been recently reported for semiconducting nanowires with proximity induced superconductivity. In this paper we analyze the relation of the zero-bias peak to the presence of Majorana end-states, by simulating the tunneling conductance for multi-band wires with realistic amounts of disorder. We show that this system generically exhibits a (non-quantized) zero-bias peak even when the wire is topologically trivial and does not possess Majorana end-states. We make comparisons to recent experiments, and discuss the necessary requirements for confirming the existence of a Majorana state.