Theoretical proposal to obtain strong Majorana evidence from scanning tunneling spectroscopy of a vortex with a dissipative environment

TL;DR

This paper proposes a method using dissipation in scanning tunneling spectroscopy to reliably identify Majorana zero modes in topological superconductors, overcoming common experimental challenges.

Contribution

It introduces a dissipation-based approach that highlights three distinct features as strong evidence for Majorana zero modes, avoiding the need for quantized conductance.

Findings

Dissipation suppresses non-Majorana conductance peaks.

Zero-bias conductance peak shows dissipation-dependent scaling.

Dissipation suppresses non-topological modes, clarifying MZM signals.

Abstract

It is predicted that a vortex in a topological superconductor contains a Majorana zero mode (MZM). The confirmative Majorana signature, i.e., the $2e^2/h$ quantized conductance, however is easily sabotaged by unavoidable interruptions, e.g. instrument broadening, non-Majorana signal, and extra particle channels. We propose to avoid the signal interruption by introducing disorder-induced dissipation that couples to the tip-sample tunneling. With dissipation involved, we highlight three features, each of which alone can provide a strong evidence to identify MZM. Firstly, dissipation suppresses a finite-energy Caroli-de Gennes-Matricon (CdGM) conductance peak into a valley, while it does not split MZM zero-bias conductance peak. Secondly, we predict a dissipation-dependent scaling feature of the zero-bias conductance peak. Thirdly, the introduced dissipation manifests the MZM signal by suppressing non-topological CdGM modes. Importantly, the observation of these features does not require a quantized conductance value $2e^2/h$.