The effect of the annealing temperature on the local distortion of La0.67Ca0.33MnO3 thin films

The colossal magnetoresistance (MR) of the La1-xCaxMnO3 system has been stu died extensively. From our previous studies, we find there is an important connection between local distortions and magnetism in these materials. Rece ntly, we have carried out Mn K-edge fluorescence experiments with thin film samples (3000 Angstrom) of La0.67Ca0.33MnO3: one is as-deposited; another one is post-annealed at 1200 K. We find that the local distortion decreases with increasing the annealing temperature. For measurements as a function of temperature, the change of the local distortion is largest for the 1200 K annealed sample. The small change for the as-deposited sample, which has the highest MR, indicates that another mechanism contributes.