Laser-Induced Magnetization Dynamics of GdFeCo Film Probing by Time Resolved Magneto-Optic Kerr Effect

Abstract

Laser-induced magnetization dynamics in Gd[Formula: see text]Fe[Formula: see text]Co[Formula: see text] (GdFeCo) film was investigated by time-resolved magneto-optical effect. After an ultrafast demagnetization and a magnetization recovery process, a second slower drop from several picoseconds (ps) to 200[Formula: see text]ps was observed. Previous report explained it as the demagnetization of Gd sublattice. However, when timescale extended up to 5 nanosecond (ns), we identified it as the part of an oscillated magnetization precession. It presents the change of magnetization orientation rather than the change of magnetization amplitude. Our results reveal that the low thermal diffusion coefficient of GdFeCo film plays an important role in the laser-induced magnetization dynamics of GdFeCo film.