Time-dependent multistate switching of topological antiferromagnetic order in Mn$_3$Sn

TL;DR

This study explores how current pulses can switch the antiferromagnetic order in Mn$_3$Sn, revealing bistable and tristable states influenced by pulse shape and temperature, with implications for spintronic device speed limits.

Contribution

It demonstrates the time-dependent switching behavior of Mn$_3$Sn's antiferromagnetic order and identifies extrinsic factors limiting its switching speed.

Findings

Switching can be bistable or tristable depending on pulse shape.

Switching involves a two-step process with demagnetization and remagnetization.

Self-heating influences the switching dynamics over tens of nanoseconds.

Abstract

The manipulation of antiferromagnetic order by means of spin-orbit torques opens unprecedented opportunities to exploit the dynamics of antiferromagnets in spintronic devices. In this work, we investigate the current-induced switching of the magnetic octupole vector in the Weyl antiferromagnet Mn$_3$Sn as a function of pulse shape, field, temperature, and time. We find that the switching behavior can be either bistable or tristable depending on the temporal structure of the current pulses. Time-resolved Hall effect measurements reveal that Mn$_3$Sn switching proceeds via a two-step demagnetization-remagnetization process caused by self-heating over a timescale of tens of ns followed by cooling in the presence of spin-orbit torques. Our results shed light on the switching dynamics of Mn$_3$Sn and prove the existence of extrinsic limits on its switching speed.