Micro-Raman evidence for topological charge order across the superconducting dome of La2-x)SrxCuO4
Abstract
The doping dependence of the micro-Raman spectra of high quality La2-xSrxCuO4 microcrystals with x=0.0-0.45 has been investigated in the region 10-300 K. The phonon at ~100 cm-1 of the orthorhombic phase shows a classical soft mode behavior up to x=0.17, supporting its correlation with the LTO to HTT transition. In the xx/yy polarization spectra of the superconducting concentrations new modes at ~150 and 370 cm-1 related to the symmetry breaking and a broad band at ~280 cm-1 are attributed to the charge ordering at temperatures well above Tc. At all temperatures studied a correlation has been found between the doping dependence of the transition temperature and the intensity of the bands at ~150, ~280, ~370 cm-1, the intensity of the La/Sr mode, and the asymmetry of the apex phonon.