SYMMETRY-DEPENDENT ELECTRONIC RAMAN-SCATTERING IN LA2-XSRXCUO4 - EVIDENCE FOR DOPING-INDUCED CHANGE IN THE KAPPA-SPACE ANISOTROPY OF CHARGE DYNAMICS

Low-frequency clectronic Raman scattering in La2-xSrxCuO4 has been investigated over a wide compositional region, 0 less-than-or-equal-to x less-than-or-equal-to 0.34, covering the insulating, superconducting, and nonsuperconducting metallic compounds. We have found that the scattering intensity for the (xy) polarization predominates over that of the (x'y') polarization in the low-doping region below x less-than-or-equal-to 0.15, but vice versa at higher doping levels. The results indicate that anisotropy in the effective-mass tensor (or k-space dispersion) of the carriers changes systematically with hole doping, in contradiction with the simple band picture.