Temperature-Dependent X-Ray Absorption Spectroscopy of Colossal Magnetoresistive Perovskites

We have measured the temperature dependence of the O K-edge pre-edge structure in the x-ray absorption spectra of the perovskites La$_{1-x}$A$_{x}$MnO$_{3}$, (A = Ca, Sr; x = 0.3, 0.4). Our measurements reveal a correlation between the disappearance of the splitting in the pre-edge region and the presence of Jahn-Teller distortions. The different magnitudes of the distortions for different compounds are proposed to explain some dissimilarity in the line shape of the spectra taken above the Curie temperature.