Temperature-dependent reflectivity studies on the non-magnetic kagome metal RbV3Sb5 in a broad energy range (50 cm−1− 20000 cm−1, equivalent to 6 meV − 2.5 eV) down to 10 K are reported. Below TCDW=102 K, the optical spectra demonstrate a prominent spectral-weight transfer from low to higher energies as the fingerprint of the charge-density wave (CDW) formation with the opening of a partial gap. A detailed analysis reveals two energy scales of, respectively, ∼ 800 cm−1 (100 meV) and 360 cm−1 (45 meV), the latter visible below 50 K only. Additionally, two modes at, respectively, 160 cm−1 (20 meV) and 430 cm−1 (53 meV) can be traced both above and below TCDW. They show strong anomalies already above TCDW with a further renormalization across the transition, suggesting the importance of the electron-phonon coupling in RbV3Sb5 in both normal and CDW states. While the 160 cm−1 mode can be attributed to the E1u phonon, the 430 cm−1 mode could not be reproduced in our phonon calculations. The antiresonance nature of this mode suggests a nontrivial electron-phonon coupling in RbV3Sb5. A distinct localization peak observed at all temperatures signals damped electron dynamics, whereas the reduced Drude spectral weight manifests moderate deviations from the band picture in RbV3Sb5.
@article{arxiv.2112.07501,
title = {Optical study of RbV$_3$Sb$_5$: Multiple density-wave gaps and phonon anomalies},
author = {M. Wenzel and B. R. Ortiz and S. D. Wilson and M. Dressel and A. A. Tsirlin and E. Uykur},
journal= {arXiv preprint arXiv:2112.07501},
year = {2022}
}