Measurement of magnetization precession for NM/Ni₈₀Fe ₂₀/NM (NM = Cu and Pt) using time-resolved Kerr effect

Magnetization precession of NM/Ni₈₀Fe₂₀/NM (NM = Cu and Pt) multilayers was measured by the time-resolved magneto-optical Kerr effect (MOKE). A MOKE measurement system equipped with a pulse laser and optical delay lines was set up and samples were combined using a photoconductive switch for pulse field generation. Clear oscillation and relaxation of the magnetization of motion in time domain were successfully observed. Gilbert damping constant α for Cu/Ni₈₀Fe₂₀/Cu multilayers was independent of the thickness of Ni₈₀Fe₂₀. While α for Pt/Ni₈₀Fe₂₀/Pt multilayers was enhanced as Ni₈₀Fe₂₀ layer became thinner. These experimental data were well fitted by LLG calculation with the same α obtained by ferromagnetic resonance (FMR).