Topological Superconducting Vortex From Trivial Electronic Bands

TL;DR

This paper demonstrates that Majorana zero modes can exist in superconducting vortices even in topologically trivial materials, challenging the belief that bulk topology is necessary for their emergence.

Contribution

It reveals that trivial electronic bands can induce vortex Majorana modes, expanding the search for Majorana fermions beyond topological superconductors.

Findings

Trivial bands in HgTe-class materials can host vortex Majorana modes.

Strain can be used to control Majorana modes in these systems.

Experimental signatures for vortex Majorana modes are proposed.

Abstract

Superconducting vortices are promising traps to confine non-Abelian Majorana quasi-particles. It has been widely believed that bulk-state topology, of either normal-state or superconducting ground-state wavefunctions, is crucial for enabling Majorana zero modes in solid-state systems. This common belief has shaped two major search directions for Majorana modes, in either intrinsic topological superconductors or trivially superconducting topological materials. Here we show that Majorana-carrying superconducting vortex is not exclusive to bulk-state topology, but can arise from topologically trivial quantum materials as well. We predict that the trivial bands in superconducting HgTe-class materials are responsible for inducing anomalous vortex topological physics that goes beyond any existing theoretical paradigms. A feasible scheme of strain-controlled Majorana engineering and experimental signatures for vortex Majorana modes are also discussed. Our work provides new guidelines for vortex-based Majorana search in general superconductors.