Field-free platform for topological zero-energy mode in superconductors LiFeAs and PbTaSe$_2$

TL;DR

This study demonstrates that magnetic Fe adatoms on topological superconductors LiFeAs and PbTaSe$_2$ can host stable zero-energy states, providing a field-free platform for Majorana modes crucial for quantum computing.

Contribution

It introduces a novel method of creating Majorana zero modes using magnetic impurities on topological superconductors without external magnetic fields.

Findings

Fe adatoms induce zero-energy bound states in superconductors.

These states do not split under magnetic fields up to 8T.

The platform is promising for quantum information applications.

Abstract

Superconducting materials exhibiting topological properties are emerging as an exciting platform to realize fundamentally new excitations from topological quantum states of matter. In this work, we explore the possibility of a field-free platform for generating Majorana zero energy excitations by depositing magnetic Fe impurities on the surface of candidate topological superconductors, LiFeAs and PbTaSe$_2$. We use scanning tunneling microscopy to probe localized states induced at the Fe adatoms on the atomic scale and at sub-Kelvin temperatures. We find that each Fe adatom generates a striking zero-energy bound state inside the superconducting gap, which do not split in magnetic fields up to 8T, underlining a nontrivial topological origin. Our findings point to magnetic Fe adatoms evaporated on bulk superconductors with topological surface states as a new platform for exploring Majorana zero modes and quantum information science under field-free conditions.