Charge Dynamics of an Unconventional Three-Dimensional Charge Density Wave in Kagome FeGe

Abstract

We report on the charge dynamics of kagome FeGe, an antiferromagnet with a charge density wave (CDW) transition at $T_{\mathrm{CDW}}\simeq 105$ K, using polarized infrared spectroscopy and band structure calculations. We reveal pronounced optical anisotropy along the $a$- and $c$-axis, as well as an unusual response associated with three-dimensional CDW order. Above $T_{\mathrm{CDW}}$, there is a notable transfer of spectral weight (SW) from high to low energies, promoted by the magnetic splitting-induced shift in bands. Across the CDW transition, we observe a sudden SW transfer from low to high energies over a broad range, along with the emergence of new excitations around 1200 cm${}^{-1}$. These results contrast with observations from other kagome metals like CsV${}_3$Sb${}_5$, where the nesting of VHSs leads to a clear CDW gap feature. Instead, our findings can be accounted for by a $2\times 2\times 2$ CDW ground state driven by a first-order structural transition involving large partial Ge1-dimerization. Our study thus unveils a complex interplay among structure, magnetism, and charge order, offering valuable insights for a comprehensive understanding of CDW order in FeGe.

8 pages, 3 figures

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Cited by in corpus (8)

• Kagome metals
• Tunability of charge density wave in a magnetic kagome metal
• Vacancy-induced suppression of CDW order and its impact on magnetic order in kagome antiferromagnet FeGe
• Intriguing kagome topological materials
• Interplay of Charge Density Wave and Magnetism on the Kagomé Lattice
• Breathing-Driven Metal-Insulator Transition in Correlated Kagome Systems
• Nature of the 1/3 Magnetization Plateau in Spin-1/2 Kagome Antiferromagnets
• Precompression engineering of metal-insulator transition and magnetism in designed breathing kagome systems