Ultrafast photoinduced ferromagnetism in the perovskite manganite Gd0.55Sr0.45MnO3.

We report the ultrafast switching of the magnetic state in the course of photoinduced phase transition from an insulator with short-range charge and orbital order (CO/OO) to a ferromagnetic metal in perovskite-type Gd_0.55Sr_0.45MnO₃. The femtosecond Kerr rotation and reflectivity measurements, which detect the spin and charge dynamics, respectively, have revealed that the metallic state is formed within the time resolution (∼200 fs); however, magnetization increases with the time constant of 0.5 ps. The relatively slow increase of the magnetization is attributable to the magnetic-field-induced alignment of ferromagnetic domains in the initially produced metallic state. [ABSTRACT FROM AUTHOR]