DIELECTRIC-RELAXATION OF LA2CUO4 AND LA1.95SR0.05CUO4-DELTA AT LOW-TEMPERATURES

La2CuO4 shows large dielectric relaxation at 31 K, the relaxation intensity is 2.5 x 10(4). At 5 K the dielectric constant of this sample is 53. This dielectric relaxation is affected by the applied voltage. Dielectric constant and conductivity increase with applied voltage. Dielectric constant at higher frequency (100 kHz) increases very slowly with temperature. The dielectric constant of La1.95Sr0.05CuO4-delta shows the same kind of character for higher frequency. However, dielectric relaxation is found in the temperature range below 4.2 K. Dielectric constant of La1.95Sr0.05CuO4-delta is about 2 x 10(5) at 4.2 K (0.1 to 10 kHz) and much larger than that of La2CuO4. This dielectric relaxation at low temperature is caused by the localized motion of hole. Hole coupling will occur and activation energy of the hole motion becomes small with increasing Strontium concentration in La2-xSrxCuO4-delta.