Skyrmions in chiral magnets with Rashba and Dresselhaus spin-orbit coupling

Skyrmions are topological spin textures of interest for fundamental science and applications. Previous theoretical studies have usually focused on chiral magnets with broken bulk inversion symmetry, with skyrmions stabilized by easy-axis anisotropy. We investigate here systems that break surface inversion (mirror symmetry) in addition to bulk inversion. This leads to two distinct Dzyaloshinskii-Moriya (DM) terms with strengths D-perpendicular to, arising from Rashba spin-orbit coupling (SOC), and D-parallel to from Dresselhaus SOC. We show that skyrmions become progressively more stable with increasing D-perpendicular to/D-parallel to and extend into the regime of easy-plane anisotropy. We find that the spin texture and topological charge density of skyrmions develops a 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 anisotropy to stabilize skyrmions in thin films, surfaces, interfaces, and bulk magnetic materials that break mirror symmetry.