Charge modulation and electron-phonon coupling strength at the Cu L3 resonance in the HTS oxychloride Ca2-xNaxCuO2Cl2

Combining high resolution RIXS and IXS we have recently unveiled bulk charge modulation in the HTS cuprates oxychloride, close to the 1/8 doping, where they are most intense, and their interaction with the Cu-O Bond stretching phonon via an intrinsic excitation of the charge modulations, which induce a shift of the phonon softening minimum away from the position of charge modulation propagation vector. To understand the nature of the charge modulation, and their interaction with the phonons, we need to explore how doping modify both the propagation vector and the phonon softening minima. Moreover, we observed that the phonon softening survive in temperature the charge modulation, suggesting its fluctuations are very robust, but we lack a detailed study of the temperature dependence for the phonon softening. We propose to answer these question, and reveal the nature of the charge modulation in cuprate oxychlorides, and their interaction with the Cu-O Bond stretching mode.