Anomalous electrons in a metallic kagome ferromagnet

• 成果类型: Article
• 署名作者: Ekahana, Sandy Adhitia; Soh, Y.; Tamai, Anna; Gosalbez-Martinez, Daniel; Yao, Mengyu; Hunter, Andrew; Fan, Wenhui; Wang, Yihao; Li, Junbo; Kleibert, Armin; Vaz, C. A. F.; Ma, Junzhang; Lee, Hyungjun; Xiong, Yimin; Yazyev, Oleg V.; Baumberger, Felix; Shi, Ming; Aeppli, G.
• 署名单位: Swiss Federal Institutes of Technology Domain; Paul Scherrer Institute; University of Geneva; Swiss Federal Institutes of Technology Domain; Ecole Polytechnique Federale de Lausanne; Swiss Federal Institutes of Technology Domain; Ecole Polytechnique Federale de Lausanne; Universitat d'Alacant; Universitat d'Alacant; Max Planck Society; Chinese Academy of Sciences; Institute of Physics, CAS; Chinese Academy of Sciences; University of Chinese Academy of Sciences, CAS; Chinese Academy of Sciences; Hefei Institutes of Physical Science, CAS; City University of Hong Kong; Anhui University; Hefei National Laboratory; Zhejiang University; Zhejiang University
• 刊物名称: Nature
• ISSN/ISSBN: 0028-6986
• DOI: 10.1038/s41586-024-07085-w
• 发表日期: 2024-03-07
• 关键词: anisotropy; state

摘要

Ordinary metals contain electron liquids within well-defined 'Fermi' surfaces at which the electrons behave as if they were non-interacting. In the absence of transitions to entirely new phases such as insulators or superconductors, interactions between electrons induce scattering that is quadratic in the deviation of the binding energy from the Fermi level. A long-standing puzzle is that certain materials do not fit this 'Fermi liquid' description. A common feature is strong interactions between electrons relative to their kinetic energies. One route to this regime is special lattices to reduce the electron kinetic energies. Twisted bilayer graphene1-4 is an example, and trihexagonal tiling lattices (triangular 'kagome'), with all corner sites removed on a 2 x 2 superlattice, can also host narrow electron bands5 for which interaction effects would be enhanced. Here we describe spectroscopy revealing non-Fermi-liquid behaviour for the ferromagnetic kagome metal Fe3Sn2 (ref. 6). We discover three C3-symmetric electron pockets at the Brillouin zone centre, two of which are expected from density functional theory. The third and most sharply defined band emerges at low temperatures and binding energies by means of fractionalization of one of the other two, most likely on the account of enhanced electron-electron interactions owing to a flat band predicted to lie just above the Fermi level. Our discovery opens the topic of how such many-body physics involving flat bands7,8 could differ depending on whether they arise from lattice geometry or from strongly localized atomic orbitals9,10. Laser-based micro-focused angle-resolved photoemission spectroscopy reveals both fractionalized and marginal quasiparticles in C3-symmetric electron pockets near the Brillouin zone centre of the ferromagnetic kagome metal Fe3Sn2.