Dynamical properties of photo-induced spin disorder in doped manganites

We have investigated dynamical properties of the spin system in a ferromagnetic (FM) La0.7Ca0.3MnO3 thin film by means of a nanosecond pump-probe method. The photo-induced transmission change measured at 2.54 eV exhibits significant temperature dependence, which is explained by photo-induced spin disorder in the FM phase. We have found that the observed temperature variation of the relaxation time near the transition temperature is well interpreted in terms of dynamical scaling theory based on a three-dimensional Heisenberg model for the second-order phase transition.