Spin wavepacket precursors in the kagome ferromagnet Fe3Sn2

Van Hove Charge Density Waves on Hexagonal Lattices and Kagome Superconductors
October 3, 2022

Monday, October 3, 2022 from 2:30-3:30 p.m.
Location: 325 Physics South Hall & Zoom
Speaker: Changmin Lee, Lawrence Berkeley National Lab

Abstract:Spin wave propagation in magnetically ordered systems has emerged as a frontier toward utilizing electron spin as active information carriers with low thermal dissipation. In this talk, I will discuss a novel mechanism of spin wave transport in the kagome ferromagnet Fe3Sn2 that exhibits two distinct magneto-crystalline anisotropy parameters. Our time-resolved magneto-optic Kerr effect (tr-MOKE) microscopy measurements reveal that optically generated spin waves can propagate across 20 µm within 100 ps through an unusual “precursor” effect. This unique light-matter interaction is enabled by the Gaussian laser pulse excitation acting on a biaxial ferromagnet that exhibits a complex dipolar spin wave dispersion at small wavevectors. The propagation precursor mechanism may hold promise toward realizing long-range, ultrafast spin wave transport in both ferromagnetic and antiferromagnetic systems.

Bio: Changmin Lee is a postdoctoral scholar working in the group of Prof. Joe Orenstein at UC Berkeley and LBNL. He started at Berkeley in 2018 following a Ph.D. work at MIT with Prof. Nuh Gedik. Changmin's current research is focused on ultrafast optical investigation of spin wave transport in magnetically ordered systems. Along with a variety of polarization microscopy setups aimed at imaging magnetic textures, he recently developed a time-resolved magneto-optic Kerr effect (tr-MOKE) microscopy that enables optical excitation and detection of propagating spin waves. 

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