Dynamics of magnetization, reversal, and ultrafast demagnetization of TbFeCo amorphous films

Abstract

Static and dynamic hysteresis loops of TbFeCo amorphous films are measured by vibrating sample magnetometry (VSM) and magneto-optical Kerr rotation. The static VSM loop shows a faster magnetization reversal than the static Kerr loop does. The dynamic Kerr hysteresis loop in a sinusoidal alternating magnetic field at 1.14kHz shows a large increase in coercivity with respect to the static coercivity. The ultrafast dynamics of laser-induced demagnetization and magnetization recovery is studied by femtosecond time-resolved polar Kerr rotation spectroscopy, and shows a subpicosecond demagnetization and several hundreds of picosecond magnetization recovery process, which suggests gigahertz writing rate possible.