Giant and anisotropic many-body spin–orbit tunability in a strongly correlated kagome magnet

• Published in: Nature (London) Vol. 562; no. 7725; pp. 91 - 95
• Main Authors: Yin, Jia-Xin, Zhang, Songtian S., Li, Hang, Jiang, Kun, Chang, Guoqing, Zhang, Bingjing, Lian, Biao, Xiang, Cheng, Belopolski, Ilya, Zheng, Hao, Cochran, Tyler A., Xu, Su-Yang, Bian, Guang, Liu, Kai, Chang, Tay-Rong, Lin, Hsin, Lu, Zhong-Yi, Wang, Ziqiang, Jia, Shuang, Wang, Wenhong, Hasan, M. Zahid
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.10.2018; Nature Publishing Group
• Subjects: 639/766/119/2792; 639/766/119/995; Anisotropy; Atomic properties; Correlation; Electromagnetism; Electron spin; Electron states; Electrons; Energy; Ferromagnetic materials; Ferromagnetism; Humanities and Social Sciences; Kagome lattice; Lattice dynamics; Letter; Magnetism; Magnetization; Microscopy; multidisciplinary; Particle spin; Physics; Physics research; Scanning tunneling microscopy; Science; Science (multidisciplinary); Spectrum analysis; Spin coupling; Spin-orbit interactions; Symmetry; Triangles; Energy Shift; Kagome Lattice; Angle-resolved Photoemission Spectroscopy (ARPES); Strong Spin-orbit Coupling (SOC); Dzyaloshinskii-Moriya Interaction
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/s41586-018-0502-7

Owing to the unusual geometry of kagome lattices—lattices made of corner-sharing triangles—their electrons are useful for studying the physics of frustrated, correlated and topological quantum electronic states 1 – 9 . In the presence of strong spin–orbit coupling, the magnetic and electronic structures of kagome lattices are further entangled, which can lead to hitherto unknown spin–orbit phenomena. Here we use a combination of vector-magnetic-field capability and scanning tunnelling microscopy to elucidate the spin–orbit nature of the kagome ferromagnet Fe 3 Sn 2 and explore the associated exotic correlated phenomena. We discover that a many-body electronic state from the kagome lattice couples strongly to the vector field with three-dimensional anisotropy, exhibiting a magnetization-driven giant nematic (two-fold-symmetric) energy shift. Probing the fermionic quasi-particle interference reveals consistent spontaneous nematicity—a clear indication of electron correlation—and vector magnetization is capable of altering this state, thus controlling the many-body electronic symmetry. These spin-driven giant electronic responses go well beyond Zeeman physics and point to the realization of an underlying correlated magnetic topological phase. The tunability of this kagome magnet reveals a strong interplay between an externally applied field, electronic excitations and nematicity, providing new ways of controlling spin–orbit properties and exploring emergent phenomena in topological or quantum materials 10 – 12 . The topological magnet Fe 3 Sn 2 exhibits a giant nematic energy shift of a many-body electronic state, demonstrating anisotropic spin–orbit tunability.