The model of the quenching of the non-equilibrium orbital angular momentum of electrons recovered by femtosecond optical pumping

The estimation is obtained for the quenching time τl of the non-equilibrium orbital momentum of the electron that can be got after the excitation by the femtosecond optical pump. The quenching process of the l is supposed to be determined by the interaction of l with the crystal field and its deformations (phonons). The time τl is determined not only by the parameters of the crystal field but also by the speed of relaxation of the virtual phonon 1/τ(ω) with the frequency ω≈1/τl. Considering the frequency dependence of τ(ω) enlarges the estimated value of τl up to the microsecond scale. This value exceeds greatly the picoseconds times of the ultrafast magnetic dynamics (UMD) processes observed after the action of the femtosecond optical pump. This means that the results obtained in our work are not supposed to be compared with the experimental data on UMD. The presented description of the quenching of l is the solution of one of the auxiliary tasks that can be useful for construction of the UMD theory.