2023 Volume 47 Issue 4 Pages 108-114
The magnetization dynamics of GdFeCo / Cu / FeCo trilayers were studied by the time-resolved magneto-optical Kerr effect (TRMOKE) using an all-optical pump-probe technique. When the pump beam was illuminated from the FeCo layer side, the magnetization precession of the GdFeCo layer was confirmed to be enhanced compared with the case without the FeCo layer. Moreover, the precession angular frequency ω and inverse of the relaxation time 1/τ of the GdFeCo layer were confirmed to be decreased by pumping the FeCo layer. The decreases in ω and 1/τ were remarkable when the external field direction approached to the film normal. We considered spin transfer torque (STT) due to the spin current injected by triggering the precession of the FeCo layer, and we obtained a positive field-like STT and negative anti-damping STT acting on the GdFeCo layer. Moreover, the spin current Js injected from the FeCo layer can be expected to be ~ 1 MA/cm2 from the magnitude of the anti-damping STT.
