Investigation of an effective anisotropy field involved in photoinduced precession of magnetization in (Ga,Mn)As

Photoinduced precession of magnetization in (Ga,Mn)As was studied for a wide range of Mn contents (0.01 <= x <= 0.11) by time-resolved magneto-optical measurements. It was found that an effective anisotropy field decreases with increasing Mn contents. Anisotropy fields were also extracted from photoinduced precession measured at different temperatures and compared with magnetization. Significant enhancement in the amplitude of oscillation in magneto-optical signals occurred with increasing pump power. The mechanism of a change in the anisotropy field with the pump power was discussed. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3073848]