RAMAN-SCATTERING OF LA2CUO4+DELTA

Raman scattering spectra of La2CuO4+delta (delta=0, 0.014,and 0.063) h ave been measured. With increasing delta, the intensity of the La vibr ation increases and its energy decreases at room temperature. This res ult suggests that the La vibration couples with the charge density wav e due to the carrier doping. In the temperature dependence of La2CuO4. 063 (Tc=40K), we have observed new mode at 120cm(-1) below 220K. This mode is assigned as the vibration of the excess oxygen along the c-axi s. This result shows the anomaly at 250K can be attributed to the free zing of the itinerancy of the excess oxygen.