Modeling Spin-Orbit Phenomena at Magnetic Interfaces

Magnetic materials lacking inversion symmetry constitute a unique platform for the exploration and control of magnetism [1]. In these systems, typically multilayers of transition metal ferromagnets and heavy metals (W, Pt, Bi₂Se₃ etc.), interfacial spin-orbit coupling promotes a wealth of physical phenomena, among which the emergence of magnetic skyrmions – topological magnetic textures –, spin-orbit torques– an efficient means to electrically control magnetization dynamics –, as well as chiral magnetic damping – energy dissipation that depends on the texture chirality. While most of the initial theoretical progress has been achieved using minimal models (e.g., the Rashba two-dimensional gas), we have recently developed a multiorbital tight-binding model of such heterostructures that enables us to model these various phenomena on equal footing and in a transparent manner [2,3]. Based on the results of this model, I will address various aspects of the interplay between spin transport and magnetism mediated by spin-orbit coupling. I will first discuss the orbital nature of interfacial spin-orbit coupling in multilayers and examine how it facilitates the onset of chiral magnetic textures. I will then present the physics of spin-orbit torques, and inspect their relation to chiral magnetic properties such as Dzyaloshinskii-Moriya interaction and chiral magnetic damping. Finally, I will discuss the current-driven dynamics of magnetic skyrmions and propose various strategies to enhance their mobility, exploiting topological spin currents flowing through the texture [4].

[1] Manchon et al., Rev. of Mod. Phys. 91, 035004 (2019)
[2] Ghosh and Manchon, Phys. Rev. B 97, 134402 (2018); 100, 014412 (2019)
[3] Manchon, Ghosh, Manchon, unpublished
[4] Abbout et al., Phys. Rev. Lett. 121, 257203 (2018).