Large anomalous Hall current induced by topological nodal lines in a ferromagnetic van der Waals semimetal

• Published in: Nature materials Vol. 17; no. 9; pp. 794 - 799
• Main Authors: Kim, Kyoo, Seo, Junho, Lee, Eunwoo, Ko, K.-T., Kim, B. S., Jang, Bo Gyu, Ok, Jong Mok, Lee, Jinwon, Jo, Youn Jung, Kang, Woun, Shim, Ji Hoon, Kim, C., Yeom, Han Woong, Il Min, Byung, Yang, Bohm-Jung, Kim, Jun Sung
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01-09-2018; Nature Publishing Group
• Subjects: 140/146; 639/301/119/995; 639/301/119/997; 639/766/119/2793; 639/766/119/995; 639/766/119/997; Biomaterials; Chemistry and Materials Science; Condensed Matter Physics; Curvature; Electron spin; Electrons; Ferromagnetic materials; Magnetic materials; Magnetism; Materials Science; Metalloids; Nanotechnology; Optical and Electronic Materials; Photoelectric emission; Topology
• ISSN: 1476-1122; 1476-4660
• DOI: 10.1038/s41563-018-0132-3

Topological semimetals host electronic structures with several band-contact points or lines and are generally expected to exhibit strong topological responses. Up to now, most work has been limited to non-magnetic materials and the interplay between topology and magnetism in this class of quantum materials has been largely unexplored. Here we utilize theoretical calculations, magnetotransport and angle-resolved photoemission spectroscopy to propose Fe
3
GeTe
2
, a van der Waals material, as a candidate ferromagnetic (FM) nodal line semimetal. We find that the spin degree of freedom is fully quenched by the large FM polarization, but the line degeneracy is protected by crystalline symmetries that connect two orbitals in adjacent layers. This orbital-driven nodal line is tunable by spin orientation due to spin–orbit coupling and produces a large Berry curvature, which leads to a large anomalous Hall current, angle and factor. These results demonstrate that FM topological semimetals hold significant potential for spin- and orbital-dependent electronic functionalities.
A combined experimental and theoretical approach identifies the van der Waals material Fe
3
GeTe
2
as a candidate ferromagnetic nodal line semimetal. These results extend the connections between topology and magnetism.