Laser-induced spin dynamics in ferromagnetic (In,Mn) As at magnetic fields up to 7 T

Laser-induced spin dynamics in (In,Mn)As is studied in magnetic fields up to 7 T. It is shown that a laser pulse can effectively excite homogenous spin precession in this compound at the frequency of the ferromagnetic resonance. Laser excitation of this resonance appears to be very ineffective if the applied magnetic field is below 1.5 T at 10 K. Our analysis shows that the damping of the laser-induced spin precession is a function of magnetic field and reaches very high values below 1.5 T.