  Time-resolved magneto-optics was used to study spin-lattice relaxation
dynamics in thin epitaxial La0.7Sr0.3MnO3 films. Two distinct recovery regimes
of the ferromagnetic order can be resolved upon photoexcitation, which manifest
themselves by two different relaxation times. A pump pulse energy independent
spin-lattice relaxation time can be deduced. Due to a weak spin-orbit coupling
in manganites this spin-lattice relaxation time is much longer than in
ferromagnetic metals. Heat flow into the substrate sets the ultimate recovery
speed of the ferromagnetic order and allows for a determination of heat
diffusion properties of manganite films.
