Majorana modes with side features in magnet-superconductor hybrid systems

TL;DR

This study uses first-principles calculations to model a magnet-superconductor hybrid system, revealing complex Majorana zero modes with side features and confirming these findings through experimental spectroscopy.

Contribution

It introduces a superconducting 80-band model derived from density functional theory for realistic MSH systems, advancing the understanding of Majorana modes in such materials.

Findings

Topological superconductivity observed across a range of parameters

Spectral weight accumulates on both sides of the magnetic chain

Experimental STM data matches theoretical spatial patterns

Abstract

Magnet-superconductor hybrid (MSH) systems represent promising platforms to host Majorana zero modes (MZMs), the elemental building blocks for fault-tolerant quantum computers. Theoretical description of such MSH structures is mostly based on simplified models, not accounting for the complexity of real materials. Here, based on density functional theory, we derive a superconducting 80-band model to study an MSH system consisting of a magnetic manganese chain on the s wave superconductor niobium. For a wide range of values of the superconducting order parameter, the system is a topological superconductor, with MZMs exhibiting non-universal spatial patterns and a drastic accumulation of spectral weight on both sides along the magnetic chain. These side feature states can be explained by an effective model which is guided by the ab initio results. Performing scanning tunneling spectroscopy experiments on the same system, we observe a spatial structure in the low-energy local density of states that is consistent with the theoretical findings. Our results open a first-principle approach to the discovery of topological superconductors.