Femtosecond magnetooptics and ultrafast magnetization reversal of ferromagnetic

Abstract The model of ultrafast magnetic dynamics to describe the magnetization switching of ferromagnetics after the action of femtosecond laser pulses is proposed. The model suggests that processes of femtosecond duration are the property of orbital rather than spin magnetism. This assumption is shown not to contradict with the existing theoretical and experimental data. The equations for the description of the optical excitation of electrons in the Bloch model of ultrafast orbital dynamics in the electric dipole approximation are obtained. They have type of Bloch equations for the artificial vector. Its two components correspond to the electric polarization created by the electric field of the light wave. The third component is expressed through the orbital angular momentum of electrons. The analysis of solutions of these equations yielded the conditions under which the optical pump leaves non-equilibrium electron orbital angular momenta. The possibility of spin switching in the spin orbital field of nonequilibrium orbital momenta is discussed.