Evidence of Magnon-Mediated Orbital Magnetism in a Quasi-2D Topological Magnon Insulator.

Alahmed, Laith; Zhang, Xiaoqian; Wen, Jiajia; Xiong, Yuzan; Li, Yi; Zhang, Li-Chuan; Lux, Fabian; Freimuth, Frank et al. · Nano Lett · 2022

basic_science · Level V

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Abstract

We explore spin dynamics in Cu(1,3-bdc), a quasi-2D topological magnon insulator. The results show that the thermal evolution of the Landé <i>g</i> factor (<i>g</i>) is anisotropic: <i>g</i><sub>in-plane</sub> decreases while <i>g</i><sub>out-of-plane</sub> increases with increasing temperature <i>T</i>. Moreover, the anisotropy of the <i>g</i> factor (Δ<i>g</i>) and the anisotropy of saturation magnetization (Δ<i>M</i><sub>s</sub>) are correlated below 4 K, but they diverge above 4 K. We show that the electronic orbital moment contributes to the <i>g</i> anisotropy at lower <i>T</i>, while the topological orbital moment induced by thermally excited spin chirality dictates the <i>g</i> anisotropy at higher <i>T</i>. Our work suggests an interplay among topology, spin chirality, and orbital magnetism in Cu(1,3-bdc).