condensed matter physics

Cavity Tuning of the CDW--Superconductivity Interplay in a Kagome Metal

arXiv:2607.27769

summary

The paper demonstrates that coupling a kagome metal (CsV₃Sb₅) to an out-of-plane polarized optical cavity can selectively soften charge‑density‑wave phonons, enhance electron‑phonon coupling, and raise the superconducting transition temperature under pressure.

Abstract

Kagome metals host competing electronic orders, including charge-density-wave (CDW) order and superconductivity, shaped by intertwined lattice, electronic-correlation, and kagome-geometric effects. Here, using quantum electrodynamical density functional theory, we identify an equilibrium cavity route for reshaping this balance in the kagome metal CsV $_{3}$ Sb $_{5}$ . An out-of-plane polarized single-mode cavity selectively softens CDW-related phonons, counteracting pressure-induced hardening and extending the CDW instability toward higher pressures. In the high-pressure regime where the CDW instability is otherwise suppressed, cavity coupling redistributes Eliashberg spectral weight toward lower frequencies, enhances the total electron--phonon coupling (EPC), and increases the EPC-based Allen--Dynes estimate of $T_{c}$ . This response originates from a charge-density redistribution induced by the out-of-plane photon mode, which modifies lattice restoring forces and drives the phonon and EPC renormalization. These results establish cavity quantum electrodynamics as a viable equilibrium route for tuning intertwined charge order, lattice dynamics, and superconductivity in kagome materials.

14 pages, 8 figures, including Supplemental Material

Topics & keywords

#cavity quantum electrodynamics #charge density wave #superconductivity #kagome lattice #electron‑phonon couplingquantum electrodynamical density functional theoryEliashberg spectral functionAllen‑Dynes Tcphonon softeningout-of-plane cavity mode