FERROMAGNETIC ORDERING AND UNUSUAL MAGNETIC ION DYNAMICS IN LA0.67CA0.33MNO3

Zero-field muon spin relaxation and resistivity experiments on La0.67C a0.33MnO3 powder show that the sublattice magnetization nu(mu)(T) is w ell described for T less than or equal to T-c by (1 - T/T-c)(beta), wh ere beta = 0.345 +/- 0.015, characteristic of a second-order phase tra nsition for a 3D spin system, and the ferromagnetic transition tempera ture (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 correlat ed, with nu(mu) proportional to - ln rho. Unusual relaxational dynamic s suggest spatially inhomogeneous Mn-ion correlation times. These resu lts are discussed in terms of the possible effects of polarons on the spin and charge dynamics.