Magnons and magnetic fluctuations in atomically thin MnBi 2 Te 4

Electron band topology is combined with intrinsic magnetic orders in MnBi Te , leading to novel quantum phases. Here we investigate collective spin excitations (i.e. magnons) and spin fluctuations in atomically thin MnBi Te flakes using Raman spectroscopy. In a two-septuple layer with non-trivial to...

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Published inNature communications Vol. 13; no. 1; p. 2527
Main Authors Lujan, David, Choe, Jeongheon, Rodriguez-Vega, Martin, Ye, Zhipeng, Leonardo, Aritz, Nunley, T Nathan, Chang, Liang-Juan, Lee, Shang-Fan, Yan, Jiaqiang, Fiete, Gregory A, He, Rui, Li, Xiaoqin
Format Journal Article
LanguageEnglish
Published England 09.05.2022
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Summary:Electron band topology is combined with intrinsic magnetic orders in MnBi Te , leading to novel quantum phases. Here we investigate collective spin excitations (i.e. magnons) and spin fluctuations in atomically thin MnBi Te flakes using Raman spectroscopy. In a two-septuple layer with non-trivial topology, magnon characteristics evolve as an external magnetic field tunes the ground state through three ordered phases: antiferromagnet, canted antiferromagnet, and ferromagnet. The Raman selection rules are determined by both the crystal symmetry and magnetic order while the magnon energy is determined by different interaction terms. Using non-interacting spin-wave theory, we extract the spin-wave gap at zero magnetic field, an anisotropy energy, and interlayer exchange in bilayers. We also find magnetic fluctuations increase with reduced thickness, which may contribute to a less robust magnetic order in single layers.
ISSN:2041-1723