Raman measurements of the superconductor (La_2-xSr_x)CuO₄

We report polarized Raman measurements of single crystal (La2-xSrx)CuO4 with x=0, 0.08, and 0.12, which encompasses insulating and superconducting crystals. Group theory predicts four Raman allowed modes of symmetry 2A1g + 2Eg. For all of the crystals we observe two sharp A1g modes at approximately 226 and 430 cm-1, but could not detect either Eg mode. Tabularly summarizing the published Raman data on this material, a great deal of disagreement can be seen among the measurements. However, our results are in good agreement with some of the data. We discuss the absence of frequency dependence on x in our data. © 1988.