Tomography of Majorana Fermions with STM Tips

TL;DR

This paper explores how scanning tunneling microscopy tips, made of normal or superconducting materials, can be used to spatially resolve Majorana fermions, revealing their localization and oscillation characteristics.

Contribution

It demonstrates the feasibility of using STM tips to detect Majorana fermion wavefunctions and analyzes the effects of tunneling strength and temperature on measurement resolution.

Findings

Superconducting STM tips improve resolution of Majorana wavefunctions.

Weak tunneling enhances the ability to observe wavefunction oscillations.

Temperature effects are minimized with superconducting leads.

Abstract

We investigate numerically the possibility to detect the spatial profile of Majorana fermions (MFs) modeling STM tips that are made of either normal or superconducting material. In both cases, we are able to resolve the localization length and the oscillation period of the MF wavefunction. We show that the tunneling between the substrate and the tip, necessary to get the information on the wave function oscillations, has to be smaller in the case of a superconducting STM. In the strong tunneling regime, the differential conductance saturates making it more difficult to observe the exponential decay of MFs. The temperature broadening of the profile is strongly suppressed in case of the superconducting lead resulting, generally, in better resolution.