The Study of the Delay Kerr Loops Induced by Femtosecond Laser Pulses in GdFeCo Film

To study the evolution of the coercivity and magnetization induced by femtosecond laser pulses in GdFeCo film at distinct pump-probe delays and reveal the laser-induced magnetization reversal process, the static delay Kerr loops were measured by the traditional time-resolved magneto-optical Kerr effect technique. The results showed that the loops contained memory effect from external field history and could not reflect the real change of coercivity and magnetization after laser pump. To eliminate the memory effect, a home-made experimental setup of photomagnetic synchronized time-resolved magneto-optical Kerr effect technology was used to measure the dynamic delay Kerr loops and reveal the real evolution of the coercivity and magnetization after laser pump, whose results are of great importance in real magneto-optical recording application.