Majorana zero modes in a magnetic and superconducting hybrid vortex

TL;DR

This paper proposes a new heterostructure platform combining ferromagnetism and superconductivity to host Majorana zero modes within hybrid vortices, utilizing an orbital effect mechanism distinct from traditional Zeeman-based approaches.

Contribution

It introduces a novel mechanism for topological phase formation relying on magnetization's orbital effects, enabling mobile Majorana modes in a hybrid magnetic-superconducting system.

Findings

Majorana zero modes can be hosted in hybrid vortices in the proposed system.

The topological phase arises from the orbital effect of magnetization, not Zeeman splitting.

The system demonstrates potential for device applications due to vortex mobility.

Abstract

We propose and investigate a new platform for the realization of Majorana zero modes in a thin-film heterostructure composed of an easy-plane ferromagnet and a superconductor with spin-orbit coupling. The system can support an energetically favorable bound state comprising a magnetic and a superconducting vortex. We show that a hybrid vortex thus created can host a robust zero-energy Majorana bound state at its core over a wide range of parameters, with its partner zero mode located at the outer boundary of a disk-shaped topological region. We identify a novel mechanism underlying the formation of the topological phase that, remarkably, relies on the orbital effect of the magnetization field and not on the usual Zeeman effect. The in-plane components of magnetization couple to electrons as a gauge potential with non-zero curl, thus creating an emergent magnetic field responsible for the gapped topologically non-trivial region surrounding the vortex core. Our construction allows the mobility of magnetic vortices to be imposed on the Majorana zero mode at the core of the superconducting vortex. In addition, the system shows a rich interplay between magnetism and superconductivity which might aid in developing future devices and technologies.