Spin wavepackets in the Kagome ferromagnet Fe<sub>3</sub>Sn<sub>2</sub>: Propagation and precursors.

Lee, Changmin; Sun, Yue; Ye, Linda; Rathi, Sumedh; Wang, Kevin; Lu, Yuan-Ming; Moore, Joel; Checkelsky, Joseph G et al. · Proc Natl Acad Sci U S A · 2023

basic_science · Level V

Where this comes from

Abstract

The propagation of spin waves in magnetically ordered systems has emerged as a potential means to shuttle quantum information over large distances. Conventionally, the arrival time of a spin wavepacket at a distance, <i>d</i>, is assumed to be determined by its group velocity, <i>v</i><sub><i>g</i></sub>. Here, we report time-resolved optical measurements of wavepacket propagation in the Kagome ferromagnet Fe<sub>3</sub>Sn<sub>2</sub> that demonstrate the arrival of spin information at times significantly less than <i>d</i>/<i>v</i><sub><i>g</i></sub>. We show that this spin wave "precursor" originates from the interaction of light with the unusual spectrum of magnetostatic modes in Fe<sub>3</sub>Sn<sub>2</sub>. Related effects may have far-reaching consequences toward realizing long-range, ultrafast spin wave transport in both ferromagnetic and antiferromagnetic systems.