Skyrmions in Chiral Magnets with Rashba and Dresselhaus Spin-Orbit Coupling

TL;DR

This paper explores how Rashba and Dresselhaus spin-orbit couplings influence the stability and structure of skyrmions in chiral magnets, providing a design principle for stabilizing skyrmions in various materials.

Contribution

It introduces a theoretical framework analyzing the combined effects of Rashba and Dresselhaus SOC on skyrmion stability and structure in systems with broken surface inversion symmetry.

Findings

Skyrmions become more stable with increasing D_perp/D_parallel ratio.

Skyrmion spin textures develop nontrivial spatial structures.

Topological charge density exhibits quantized values related to a Chern number.

Abstract

Skyrmions are topological spin textures of interest for fundamental science and applications. Previous theoretical studies have focused on systems with broken bulk inversion symmetry, where skyrmions are stabilized by easy-axis anisotropy. We investigate here systems that break surface inversion symmetry, in addition to possible broken bulk inversion. This leads to two distinct Dzyaloshinskii-Moriya (DM) terms with strengths $D_\perp$, arising from Rashba spin-orbit coupling (SOC), and $D_\parallel$ from Dresselhaus SOC. We show that skyrmions become progressively more stable with increasing $D_\perp/D_\parallel$, extending into the regime of easy-plane anisotropy. We find that the spin texture and topological charge density of skyrmions develops nontrivial spatial structure, with quantized topological charge in a unit cell given by a Chern number. Our results give a design principle for tuning Rashba SOC and magnetic anisotropy to stabilize skyrmions in thin films, surfaces, interfaces and bulk magnetic materials that break mirror symmetry.