3/8 charge-density wave instability in the kagome metal CsV3Sb5
Abstract
The kagome metal CsV3Sb5 exhibits charge density wave (CDW) and superconducting transitions, both of which are substantially affected by pressure. Recent x-ray diffraction experiments identify a new charge-ordered phase at a pressure coinciding with the dip of the superconducting dome. This CDW phase displays a distinctive wavevector Q = (3/8, 0, 1/2) and monoclinic symmetry, in contrast to the 2×2× 2 and 2×2× 4 orders reported at ambient pressure. In this letter, we show that density functional perturbation theory (DFPT) calculations on a fine reciprocal-space grid predict the leading lattice instability of CsV3Sb5 to be at this wavevector. Finite-displacement calculations reveal that while anharmonic effects stabilize the conventional L2- CDW at ambient pressure, the competing 3/8 instability becomes energetically favorable above ∼1 GPa, consistent with experimental observations. Interestingly, the nesting function displays a peak at the same wavevector. A Landau free energy analysis explains the emergence of the monoclinic distortion observed in x-ray diffraction, in addition to several bond-ordering patterns that may be relevant to the observed trends in the superconducting Tc.
Related
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BibTeX
@misc{buiarelli2026chargedensity,
title = {{3/8 charge-density wave instability in the kagome metal CsV$_3$Sb$_5$}},
author = {Luca Buiarelli and Hyeonseo H. Park and Ethan T. Ritz and Rafael M. Fernandes and Turan Birol},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.38071},
eprint = {2609.38071},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.38071},
}
RIS
TY - UNPB
TI - 3/8 charge-density wave instability in the kagome metal CsV_3Sb_5
AU - Luca Buiarelli
AU - Hyeonseo H. Park
AU - Ethan T. Ritz
AU - Rafael M. Fernandes
AU - Turan Birol
PY - 2026
DA - 2026/09/29
PB - arXiv
DO - 10.48550/arxiv.2609.38071
UR - https://arxiv.org/abs/2609.38071
AB - The kagome metal CsV_3Sb_5 exhibits charge density wave (CDW) and superconducting transitions, both of which are substantially affected by pressure. Recent x-ray diffraction experiments identify a new charge-ordered phase at a pressure coinciding with the dip of the superconducting dome. This CDW phase displays a distinctive wavevector Q = (3/8, 0, 1/2) and monoclinic symmetry, in contrast to the 2×2× 2 and 2×2× 4 orders reported at ambient pressure. In this letter, we show that density functional perturbation theory (DFPT) calculations on a fine reciprocal-space grid predict the leading lattice instability of CsV_3Sb_5 to be at this wavevector. Finite-displacement calculations reveal that while anharmonic effects stabilize the conventional L_2^- CDW at ambient pressure, the competing 3/8 instability becomes energetically favorable above ∼1 GPa, consistent with experimental observations. Interestingly, the nesting function displays a peak at the same wavevector. A Landau free energy analysis explains the emergence of the monoclinic distortion observed in x-ray diffraction, in addition to several bond-ordering patterns that may be relevant to the observed trends in the superconducting T_c.
ER -