Time-resolved photo-induced nonlinear magneto-optical Kerr effect for the study of surface spin dynamics
Résumé
We introduce time-resolved photo-induced nonlinear magneto-optical Kerr-effect measurements as a tool for studying spin dynamics on the femtosecond time-scale at a GaAs surface. Circularly polarized pump pulses induce a spin polarization in the sample, i.e., a transient magnetization
that can be followed by magnetically-induced second harmonic generation from delayed probe pulses. We also show that measuring the sum frequency generation due to the coherent interaction of pump and probe pulses can lead to such temporal information as well. Initial results show that
a rapid spin relaxation occurs in a time shorter than the pulse duration of our experiment i.e. less than 50 fs.