# Mixed Weyl semimetals and dissipationless magnetization control in insulators by spin-orbit torques

## TL;DR

This paper predicts that topologically non-trivial magnetic insulators, specifically mixed Weyl semimetals, can exhibit exceptionally strong spin-orbit torques and Dzyaloshinskii-Moriya interactions, enabling efficient magnetization control without currents.

## Contribution

It introduces the concept of mixed Weyl semimetals in magnetic insulators and links their topology to enhanced spin-orbit torques and topological phase transitions.

## Key findings

- Spin-orbit torques in these insulators can surpass those in metallic magnets.
- Magnetic monopoles in electronic structure drive the topological response.
- The work connects topology with magneto-electric phenomena in insulators.

## Abstract

Reliable and energy efficient magnetization switching by electrically-induced spin-orbit torques is of crucial technological relevance for spintronic devices implementing memory and logic functionality. Here we predict that the strength of spin-orbit torques and the related Dzyaloshinskii-Moriya interaction in topologically non-trivial magnetic insulators can exceed by far that of conventional metallic magnets. In analogy to the quantum anomalous Hall effect, we explain this extraordinary response in absence of longitudinal currents as a hallmark of magnetic monopoles in the electronic structure of systems that are interpreted most naturally within the framework of mixed Weyl semimetals. We thereby launch the effect of spin-orbit torque into the field of topology and reveal its crucial role in mediating the topological phase transitions arising due to the complex interplay between magnetization direction and momentum-space topology. The concepts presented here may be exploited to understand and utilize magneto-electric coupling phenomena in insulating ferromagnets and antiferromagnets.