Mapping the Rich Electronic Landscape of Distorted Kagome Metals

日時　2026年1月29日　（木）　13:30 – 14:30
場所　WPI-SKCM2研究棟（VBL）　2階　セミナー室（VBL204）
講師　Anup Pradhan Sakhya
(Research Institute for Synchrotron Radiation Science, Hiroshima University)

Quantum materials featuring a kagome lattice, in which corner-sharing triangles form a hexagonal framework, provide a unique platform to explore the interplay between lattice geometry, electron correlations, and spin interactions, and have attracted considerable attention in recent years [1]. In this talk, I will introduce LnTi₃Bi₄ (Ln = lanthanide), a novel family of distorted kagome metals that has drawn interest due to the combination of highly anisotropic magnetism and a rich electronic structure [2]. I will present a comparative ARPES and DFT study of several members of this series, highlighting their diverse yet interconnected electronic phenomena. In YbTi₃Bi₄, NdTi₃Bi₄, and LaTi₃Bi₄, we directly observe multiple van Hove singularities near the Fermi level, linearly dispersing Dirac-like states, and flat bands arising from destructive interference within the Ti-based kagome network [3-5]. These features are accompanied by strong electronic anisotropy, reflecting the broken sixfold rotational symmetry inherent to the distorted kagome lattice. I will also briefly discuss CeTi₃Bi₄, where the Ti kagome electronic structure couples to localized Ce³⁺ moments, giving rise to a rich magnetic phase diagram including a spin-density-wave ground state [6]. Together, these results establish LnTi₃Bi₄ as a versatile model system in which flat-band physics, Dirac topology, Fermi-surface instabilities, and magnetism can be systematically explored within a single materials family.

[1] Y. Wang et al., Nat Rev Phys 5, 635–658 (2023).
[2] B. R. Ortiz et al., Chem. Mater. 35, 9756 (2023).
[3] A. P. Sakhya et al., Commun. Mater. 5, 241 (2024).
[4] M. I. Mondal*, A. P. Sakhya* et al., Phys. Rev. B 112, L121104 (2025).
[5] A. P. Sakhya et al., Phys. Rev. Mater. 9, L111201 (2025).
[6] P. Park, B. R. Ortiz, M. Sprague, A. P. Sakhya et al., Nat Commun 16, 4384 (2025).

問合せ先　出田真一郎（放射光科学研究所）