Synthesis of a semimetallic Weyl ferromagnet with point Fermi surface
成果类型：
Article
署名作者：
Belopolski, Ilya; Watanabe, Ryota; Sato, Yuki; Yoshimi, Ryutaro; Kawamura, Minoru; Nagahama, Soma; Zhao, Yilin; Shao, Sen; Jin, Yuanjun; Kato, Yoshihiro; Okamura, Yoshihiro; Zhang, Xiao-Xiao; Fujishiro, Yukako; Takahashi, Youtarou; Hirschberger, Max; Tsukazaki, Atsushi; Takahashi, Kei S.; Chiu, Ching-Kai; Chang, Guoqing; Kawasaki, Masashi; Nagaosa, Naoto; Tokura, Yoshinori
署名单位：
RIKEN; University of Tokyo; University of Tokyo; Nanyang Technological University; Huazhong University of Science & Technology; Huazhong University of Science & Technology; RIKEN; Tohoku University; RIKEN; University of Tokyo
刊物名称：
Nature
ISSN/ISSBN：
0028-2684
DOI：
10.1038/s41586-024-08330-y
发表日期：
2025-01-30
关键词：
摘要：
Quantum materials governed by emergent topological fermions have become a cornerstone of physics. Dirac fermions in graphene form the basis for moir & eacute; quantum matter and Dirac fermions in magnetic topological insulators enabled the discovery of the quantum anomalous Hall (QAH) effect1, 2-3. By contrast, there are few materials whose electromagnetic response is dominated by emergent Weyl fermions4, 5-6. Nearly all known Weyl materials are overwhelmingly metallic and are largely governed by irrelevant, conventional electrons. Here we theoretically predict and experimentally observe a semimetallic Weyl ferromagnet in van der Waals (Cr,Bi)2Te3. In transport, we find a record bulk anomalous Hall angle of greater than 0.5 along with non-metallic conductivity, a regime that is strongly distinct from conventional ferromagnets. Together with symmetry analysis, our data suggest a semimetallic Fermi surface composed of two Weyl points, with a giant separation of more than 75% of the linear dimension of the bulk Brillouin zone, and no other electronic states. Using state-of-the-art crystal-synthesis techniques, we widely tune the electronic structure, allowing us to annihilate the Weyl state and visualize a unique topological phase diagram exhibiting broad Chern insulating, Weyl semimetallic and magnetic semiconducting regions. Our observation of a semimetallic Weyl ferromagnet offers an avenue towards new correlated states and nonlinear phenomena, as well as zero-magnetic-field Weyl spintronic and optical devices.