Shot-noise and differential conductance as signatures of putative topological superconductivity in FeSe$_{0.45}$Te$_{0.55}$

TL;DR

This paper proposes a theoretical framework linking shot-noise and differential conductance measurements as universal signatures of Majorana zero modes in topological superconductors like FeSe$_{0.45}$Te$_{0.55}$, independent of electronic details.

Contribution

It introduces a universal theoretical prediction that vanishing differential shot noise alongside quantized differential conductance signals Majorana modes in 2D topological superconductors.

Findings

$dS/dV$ vanishes when $dI/dV$ is quantized near Majorana modes.

Results are independent of the orbital tunneling path.

Universal signatures for Majorana modes in complex materials.

Abstract

We present a theory for the differential shot noise, $dS/dV$, as measured via shot-noise scanning tunneling spectroscopy, and the differential conductance, $dI/dV$, for tunneling into Majorana zero modes (MZMs) in the putative topological superconductor FeSe$_{0.45}$Te$_{0.55}$. We demonstrate that for tunneling into chiral Majorana edge modes near domain walls, as well as MZMs localized in vortex cores and at the end of defect lines, $dS/dV$ vanishes whenever $dI/dV$ reaches a quantized value proportional to the quantum of conductance. These results are independent of the particular orbital tunneling path, thus establishing a vanishing $dS/dV$ concomitant with a quantized $dI/dV$, as universal signatures for Majorana modes in two-dimensional topological superconductors, irrespective of the material's specific complex electronic bandstructure.