Mode-selective electron-phonon coupling drives charge density waves in the kagome metals YRu3Si2 and LaRu3Si2
Abstract
YRu3Si2 and LaRu3Si2 host the highest charge density wave (CDW) transition temperatures ever reported in kagome metals, TCDW≈ 800 and 400~K, with propagation vectors QCDW≈(1/2,0,0) and $(1/4,0,0)$, respectively. The microscopic mechanism behind these record values has remained unresolved. Here, we combine anharmonic phonon renormalization extracted from molecular dynamics driven by a machine-learned force field with mode-resolved electron-phonon coupling (EPC) analysis to identify this mechanism. The CDW is driven by mode-selective EPC: the Ru out-of-plane phonon modes couple the Ru-dxz/dyz and Si-px/py orbitals, and the phonon linewidth peaks sharply at QCDW, while the featureless electronic susceptibility rules out Fermi-surface nesting. Phonon anharmonicity melts the CDW, and the anharmonic phonon spectra reproduce both QCDW and TCDW in good agreement with experiments. Molecular dynamics simulations also visualize the CDW melting in real space. Chemical bonding analysis further shows that the smaller Y3+ radius strengthens the Ru-Ru bonds, enhancing lattice rigidity and accounting for the factor-of-two higher TCDW of YRu3Si2. Our results establish a unified microscopic picture of CDW formation and melting in kagome metals YRu3Si2 and LaRu3Si2.
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BibTeX
@misc{tu2026modeselective,
title = {{Mode-selective electron-phonon coupling drives charge density waves in the kagome metals YRu$_3$Si$_2$ and LaRu$_3$Si$_2$}},
author = {Wenqian Tu and Run Lv and Dingfu Shao and Yuping Sun and Wenjian Lu},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.11689},
eprint = {2610.11689},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.11689},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Mode-selective electron-phonon coupling drives charge density waves in the kagome metals YRu_3Si_2 and LaRu_3Si_2
AU - Wenqian Tu
AU - Run Lv
AU - Dingfu Shao
AU - Yuping Sun
AU - Wenjian Lu
PY - 2026
DA - 2026/10/08
PB - arXiv
DO - 10.48550/arxiv.2610.11689
UR - https://arxiv.org/abs/2610.11689
AB - YRu_3Si_2 and LaRu_3Si_2 host the highest charge density wave (CDW) transition temperatures ever reported in kagome metals, T_CDW≈ 800 and 400~K, with propagation vectors Q_CDW≈(1/2,0,0) and $(1/4,0,0)$, respectively. The microscopic mechanism behind these record values has remained unresolved. Here, we combine anharmonic phonon renormalization extracted from molecular dynamics driven by a machine-learned force field with mode-resolved electron-phonon coupling (EPC) analysis to identify this mechanism. The CDW is driven by mode-selective EPC: the Ru out-of-plane phonon modes couple the Ru-d_xz/d_yz and Si-p_x/p_y orbitals, and the phonon linewidth peaks sharply at Q_CDW, while the featureless electronic susceptibility rules out Fermi-surface nesting. Phonon anharmonicity melts the CDW, and the anharmonic phonon spectra reproduce both Q_CDW and T_CDW in good agreement with experiments. Molecular dynamics simulations also visualize the CDW melting in real space. Chemical bonding analysis further shows that the smaller Y^3+ radius strengthens the Ru-Ru bonds, enhancing lattice rigidity and accounting for the factor-of-two higher T_CDW of YRu_3Si_2. Our results establish a unified microscopic picture of CDW formation and melting in kagome metals YRu_3Si_2 and LaRu_3Si_2.
ER -