Composite Topological Excitations in Ferromagnet-Superconductor Heterostructures

TL;DR

This paper explores the formation and control of a novel composite topological excitation, the skyrmion-vortex pair, in ferromagnet-superconductor heterostructures, revealing how spin-orbit interaction mediates their interaction.

Contribution

It introduces the concept of skyrmion-vortex pairs in hybrid systems and analyzes their formation, interaction, and controllability using analytical and numerical methods.

Findings

Bound SVPs depend on topological indices and interaction sign.

Analytical and numerical methods characterize the binding potential.

SVPs can be manipulated via applied spin currents.

Abstract

We investigate the formation of a new type of composite topological excitation -- the skyrmion-vortex pair (SVP) -- in hybrid systems consisting of coupled ferromagnetic and superconducting layers. Spin-orbit interaction in the superconductor mediates a magnetoelectric coupling between the vortex and the skyrmion, with a sign (attractive or repulsive) that depends on the topological indices of the constituents. We determine the conditions under which a bound SVP is formed, and characterize the range and depth of the effective binding potential through analytical estimates and numerical simulations. Furthermore, we develop a semiclassical description of the coupled skyrmion-vortex dynamics and discuss how SVPs can be controlled by applied spin currents.