Difference between the cleaved surface and the polished surface on the   Raman spectra of La$_{2-x}$Sr$_x$CuO$_4$
  The 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. 
S. Sugai, Y. Takayanagi, and N. Hayamizu