2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/16886The Raman spectra on the cleaved surface of La$_{2-x}$Sr$_x$CuO$_4$ is found to be different from those on the mechanically polished or chemically etched surface. On the cleaved surface, the step-like increase of the scattering intensity below 700 cm$^{-1}$ is washed away and the two-phonon peaks are preserved clearly even at the optimum doping. The difference is demonstrated on the optimally doped crystal at x=0.15 and the stripe phase crystal at x=0.115. The stripe phase is stabilized by defects induced by mechanical polishing.9 pages, 4 figuresSuperconductivityStrongly Correlated Electronstext