Charge Ordering and Polaron Formation in the Magnetoresistive OxideLa0.7Ca0.3MnO3

Neutron scattering has been used to study the nature of the ferromagnetic transition in a single crystal of the perovskite ${\mathrm{La}}_{0.7}{\mathrm{Ca}}_{0.3}{\mathrm{MnO}}_3$. Diffuse scattering from lattice polarons develops as the Curie temperature is approached from below, along with short range polaron correlations that are consistent with stripe formation. Both the scattering due to the polaron correlations and the anomalous quasielastic component in the magnetic fluctuation spectrum maximize very close to $T_C$, in a manner remarkably similar to the resistivity, indicating that they have a common origin.