Evidence of Magnon-Mediated Orbital Magnetism in a Quasi-2D Topological Magnon Insulator
Laith Alahmed, Xiaoqian Zhang, Jiajia Wen, Yuzan Xiong, Yi Li, Lichuan Zhang, Fabian R. Lux, Frank Freimuth, Muntasir Mahdi, Yuriy Mokrousov, V. Novosad, W. K. Kwok, Dapeng Yu, Wei Zhang, Young S. Lee, Peng Li
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 g factor (g) is anisotropic: gin-plane decreases while gout-of-plane increases with increasing temperature T. Moreover, the anisotropy of the g factor (Δg) and the anisotropy of saturation magnetization (ΔMs) are correlated below 4 K, but they diverge above 4 K. We show that the electronic orbital moment contributes to the g anisotropy at lower T, while the topological orbital moment induced by thermally excited spin chirality dictates the g anisotropy at higher T. Our work suggests an interplay among topology, spin chirality, and orbital magnetism in Cu(1,3-bdc).