ESR STUDIES ON GMR RELATED MATERIALS IV: ESR OF Mn IN La0.7Ca0.3MnO3

ESR measurements have been carried out on La0.7Ca0.3MnO3. Distorted signals have been observed below about 255 K, but clear signals above ≃ 270 K. The temperature dependence of the low-temperature ESR linewidth nearly follows the magnetization (or susceptibility). The ESR intensity exhibits an anomalous increase at temperatures between about 200 K and 260 K with a peak at around 250 K; quite similar behavior to that of the resistivity, indicating a possible correlation between the resistivity and the ESR intensity. The temperature dependence of the ESR linewidth and intensity has been also studied above 300 K.