Direct relationship between magnetism and MnO6 distortions in La1-xCaxMnO3

Measured distortions of the Mn-O bond length distribution from x-ray-absorption fine-structure measurements are found to relate linearly to the doped hole concentration x at room temperature in La1-xCaxMnO3. Comparison of the distortions above and below T-c for colossal magnetoresistor (CMR) samples gives an estimate of the number of delocalized holes n(dh), and we find that ln(n(dh)) proportional to M (magnetization). These results are complementary to resistance measurements that show that ln(rho) proportional to -M. We have thus established the functional relationship between the electronic, spin, and lattice degrees of freedom in the CMR perovskites.