We measure the dispersion of the Cu-O bond-stretching phonon mode in the high-temperature superconducting parent compound Ca2CuO2Cl2. Our density functional theory calculations predict a cosine-shaped bending of the dispersion along both the (ξ00) and (ξξ0) directions, while comparison with previous results on Ca1.84CuO2Cl2 show it only along (ξ00), suggesting an anisotropic effect which is not reproduced in calculation at optimal doping. Comparison with isostructural La2−xSrxCuO4 suggests that these calculations reproduce well the overdoped regime, however they overestimate the doping effect on the Cu-O bond-stretching mode at optimal doping.
@article{arxiv.1904.08258,
title = {Phonon anomalies with doping in superconducting oxychlorides Ca2-xCuO2Cl2},
author = {Blair W. Lebert and Hajime Yamamoto and Masaki Azuma and Rolf Heid and Satoshi Tsutsui and Hiroshi Uchiyama and Alfred Q. R. Baron and Benoît Baptiste and Matteo d'Astuto},
journal= {arXiv preprint arXiv:1904.08258},
year = {2020}
}