Evidence for a local lattice distortion in Ca-doped LaMnO3

We have found that a significant change in the local structure of ${\mathrm{La}}_{\frac{2}{3}}{\mathrm{Ca}}_{\frac{1}{3}}\mathrm{Mn}{\mathrm{O}}_3$ occurs between 80 K and temperatures above the Curie temperature, $T_c=270\mathrm{}$ K. Near-edge x-ray-absorption spectra exhibits changes between 80 K and above $T_c$. X-ray-absorption fine structure reveals differences between the nearest-neighbor Mn-O bond distributions at 80 K and above $T_c$. The single-site distribution at low temperature becomes a complex, multi-site distribution above $T_c$. The observed change is consistent with proposed small polaron related local Jahn-Teller distortions for $T>\mathrm{}{T}_c$.