Giant effective damping of octupole oscillation in an antiferromagnetic Weyl semimetal

TL;DR

This paper reports the first observation of ultrafast octupole oscillations in an antiferromagnetic Weyl semimetal, revealing giant damping and potential for sub-10 ps switching, advancing topological antiferromagnetic device research.

Contribution

It demonstrates ultrafast octupole dynamics and giant damping in Mn3Sn, a topological antiferromagnet, enabling rapid switching and domain wall motion predictions.

Findings

Giant effective damping of octupole oscillation in Mn3Sn

Ultrafast switching potential below 10 ps

High domain wall velocity over 10 km/s predicted

Abstract

A magnetic Weyl semimetal is a recent focus of extensive research as it may exhibit large and robust transport phenomena associated with topologically protected Weyl points in momentum space. Since a magnetic texture provides a handle for the configuration of the Weyl points and its transport response, understanding of magnetic dynamics should form a basis of future control of a topological magnet. Mn3Sn is an example of an antiferromagnetic Weyl semimetal that exhibits a large response comparable to the one observed in ferromagnets despite a vanishingly small magnetization. The non-collinear spin order in Mn3Sn can be viewed as a ferroic order of cluster magnetic octupole and breaks the time-reversal symmetry, stabilizing Weyl points and the significantly enhanced Berry curvature near the Fermi energy. Here we report our first observation of time-resolved octupole oscillation in Mn3Sn. In particular, we find the giant effective damping of the octupole dynamics, and it is feasible to conduct an ultrafast switching at < 10 ps, a hundred times faster than the case of spin-magnetization in a ferromagnet. Moreover, high domain wall velocity over 10 km/s is theoretically predicted. Our work paves the path towards realizing ultrafast electronic devices using the topological antiferromagnet.