Ferromagnetic ordering and unusual magnetic ion dynamics in La0.67Ca0.33MnO3

Zero-field muon spin relaxation and resistivity experiments on La0.67Ca0.33MnO3 powder show that the sublattice magnetization nu(mu)(T) is well described for T less than or equal to T-c by (1 - T/T-c)(beta), where beta = 0.345 +/- 0.015, characteristic of a second-order phase transition for a 3D spin system, and the ferromagnetic transition temperature (T-c = 274 K) and resistivity peak temperature coincide to within 1 K. Below T-C nu(mu) and the zero-field resistivity rho are correlated, with nu(mu) proportional to - ln rho. Unusual relaxational dynamics suggest spatially inhomogeneous Mn-ion correlation times. These results are discussed in terms of the possible effects of polarons on the spin and charge dynamics.