Fermi-level flat band in a kagome magnet

作者：T. Y. Yang, Qiang Wan, Jiajiong Song, Zhiwei Du, Jingling Tang, Z. W. Wang, N. C. Plumb, M. Radović, G. W. Wang, G. Y. Wang, Zhe Sun, Jia‐Xin Yin, Zhenhua Chen, Yuan Huang, Rui Yu, M. Shi, Yimin Xiong, Nan Xu · 发表于：Quantum Frontiers · 年份：2022 · DOI：10.1007/s44214-022-00017-7 · 被引用次数：26 · 研究领域：Advanced Condensed Matter Physics、Topological Materials and Phenomena、Physics of Superconductivity and Magnetism

Abstract The band structure in a kagome lattice can naturally exhibit flat band, Dirac cones, and van Hove singularity, enabling rich interplays between correlation and topology. However, the flat band is rarely detected just at the Fermi level in kagome materials, which would be crucial to realize emergent flat band physics. Here, combining angle-resolved photoemission spectroscopy, transport measurements and first-principles calculation, we observe a striking Fermi-level flat band in paramagnetic YCr 6 Ge 6 as a typical signature of electronic kagome lattice. We explicitly unveil that orbital character plays an essential role to realize electronic kagome lattice in crystals with transition-metal kagome layers. We further engineer this material with magnetic rare earth elements to break the time-reversal symmetry of the Fermi-level kagome flat band. Our work establishes a Fermi-level flat band in a kagome magnet as an exciting quantum platform.