We report optical spectra of Lu5Ir4Si10 and Er5Ir4Si10, exhibiting the phenomenon of coexisting superconductivity or antiferromagnetism and charge density wave (CDW) order. We measure the maximum value of the charge density wave gap present on part of the Fermi surface of Lu5Ir4Si10, corresponding to a ratio 2\Delta/k_B T_CDW \approx 10, well above the value in the limit of weak electron-phonon coupling. Strong electron-phonon coupling was confirmed by analyzing the optical conductivity with the Holstein model describing the electron-phonon interactions, indicating the coupling to phonons centered at 30 meV, with a coupling constant \lambda \approx 2.6. Finally we provide evidence that approximately 16 % of the Fermi surface of Lu5Ir4Si10 becomes gapped in the CDW state.
@article{arxiv.0812.1214,
title = {Evidence for strongly coupled charge-density-wave ordering in three-dimensional RE5Ir4Si10 compounds by optical measurements},
author = {Riccardo Tediosi and Fabrizio Carbone and A. B. Kuzmenko and J. Teyssier and D. van der Marel and J. A. Mydosh},
journal= {arXiv preprint arXiv:0812.1214},
year = {2009}
}