Zero-field superconducting vortices and Majorana zero modes pinned by magnetic islands in correlated Rashba systems

TL;DR

This paper presents a novel method for stabilizing zero-field superconducting vortices and Majorana zero modes using magnetic islands in Rashba systems with magnetic correlations but no long-range order.

Contribution

It introduces a new approach to pin vortices and Majorana modes in correlated Rashba superconductors without requiring magnetic order, expanding potential experimental platforms.

Findings

Predicts emergence of zero-field vortices and Majorana modes in topological insulator surfaces.

Shows inhomogeneous magnetization gradients induce vorticity in superconductors.

Provides a framework for trapping vortex-Majorana excitations in accessible systems.

Abstract

We propose a route for pinning zero-field superconducting vortices in systems which are exchange-coupled to magnetic islands and feature Rashba spin-orbit coupling. We consider islands with sizes which greatly exceed those of the vortex cores and possess out-of-plane magnetic moments. A crucial ingredient of our approach is that it considers superconductors which are governed by magnetic correlations without, however, exhibiting long range magnetic order. The arising total magnetization is inhomogeneous and its gradients generate a nonzero vorticity in the superconducting phase. Vortices become energetically stable due to the energy reduction brought about from the generation of electronic magnetization. Using our developed framework, we make concrete predictions for the emergence of zero-field vortices and Majorana zero modes in superconducting topological insulator surfaces and planar Rashba superconductors. Our theory uncovers a nonstandard path for trapping composite vortex-Majorana excitations in systems which appear to be within experimental reach.