Dynamical Coupling and Separation of Multiple Degrees of Freedom in a Photoexcited Double-Exchange System

We present a theory of ultrafast photoinduced dynamics in a spin-charge coupled system, motivated by pump-probe experiments in perovskite manganites. A microscopic picture for multiple dynamics in spin and charge degrees is examined. Real-time simulations are carried out by two complimentary methods. Our calculation demonstrates that electron motion governs a short-time scale where charge and spin dynamics are combined strongly, while, in a long-time scale controlled by spin relaxation, the charge sector does not follow the remarkable change in the spin sector. The present results are in contrast to a conventional double-exchange picture in equilibrium states.