Submicron-scale spatial feature of ultrafast photoinduced magnetization reversal in TbFeCo thin film

Submicron-scale spatial feature of magnetization reversal dynamics induced by femtosecond optical pulse irradiation in a small external magnetic field was investigated by time-resolved magneto-optical Kerr microscopy on TbFeCo thin film. The magnetization reversal time near the magnetic domain boundary is dominated by an effective magnetic field generated from the peripheral domain by dipole-dipole interaction. The magnetization reversal is accelerated as high as 4.5 times (from 3.4 ns to 750 ps) when reducing the reversed domain size from 1.5 to 0.4 μm due to concentration of dipole-dipole interaction.