Dynamics of photoinduced magnetization rotation in ferromagnetic semiconductor p-(Ga,Mn)As

Dynamics of photoinduced magnetization rotation was studied in ferromagnetic p-(Ga,Mn)As by carefully comparing the temporal profile of the photoinduced polar Kerr rotation with that of the photoinduced reflectivity change. Rotation of ferromagnetically coupled Mn spins is induced by photogenerated hole spins within the excitation pulse width of a 100 fs, whereas relaxation takes place in tens of picosecond as a result of strong damping. Observed results suggest that hole and Mn spins rotate and relax together upon optical excitation. This would be a different type of excitation (coupled hole-Mn spin complex) appearing in the hole-mediated ferromagnetic system.