Observation of two time scales in the ferromagnetic manganite La1-xCaxMnO3, x≈0.3

We report new zero-field muon spin relaxation and neutron spin echo measurements in ferromagnetic (FM) (La,Ca)MnO3 which suggest at least two spatially separated regions possessing very different Mn-ion spin dynamics. One region displays diffusive relaxation, critical slowing down near T-C and an increasing volume fraction below T-C, suggesting overdamped FM spinwaves below T-C. The second region possesses more slowly fluctuating spins, a linewidth independent of q, and a decreasing volume fraction below T-C. The estimated length scale for the inhomogeneity is less than or equal to 30 Angstrom.