Intrinsic non-adiabatic topological torque in magnetic skyrmions and vortices

TL;DR

This paper introduces an intrinsic non-adiabatic torque in topologically non-trivial magnetic textures like skyrmions and vortices, explaining enhanced non-adiabaticity and influencing their motion and robustness.

Contribution

It proposes a new form of topological spin torque specific to magnetic skyrmions and vortices, absent in simpler textures, advancing understanding of their dynamics.

Findings

Identifies an intrinsic non-adiabatic torque in topological textures.

Explains the enhanced non-adiabaticity parameter in vortices.

Highlights the torque's role in skyrmion robustness against defects.

Abstract

We propose that topological spin currents flowing in topologically non-trivial magnetic textures, such as magnetic skyrmions and vortices, produce an intrinsic non-adiabatic torque of the form ${\bf T}_t\sim [(\partial_x{\bf m}\times\partial_y{\bf m})\cdot{\bf m}]\partial_y{\bf m}$. We show that this torque, which is absent in one-dimensional domain walls and/or non-topological textures, is responsible for the enhanced non-adiabaticity parameter observed in magnetic vortices compared to one-dimensional textures. The impact of this torque on the motion of magnetic skyrmions is expected to be crucial, especially to determine their robustness against defects and pinning centers.