Perpendicular magnetic anisotropy and Gilbert damping of MgO/Co_100–xFe_x/Pt trilayers

Abstract Perpendicular magnetic anisotropy and Gilbert damping of MgO/Co 100– x Fe x /Pt ( x = 20, 50) trilayers before and after annealing at 200–400 °C were evaluated by hysteresis loop and time-resolved magneto-optical Kerr effect (TRMOKE) measurements. The anisotropy field of the trilayers increased with reducing the CoFe thickness, which reflects the anisotropy is originated from the interface. The annealing around 300 °C was effective to increase the anisotropy because the roughness of the MgO/CoFe interface was reduced by annealing. The effective Gilbert damping α eff also increased with reducing CoFe thickness and increasing annealing temperature. The increase of α eff was considered to be promoted by the interdiffusion between CoFe and Pt after annealing. Small α eff and large perpendicular anisotropy were confirmed to be obtained using Co 50 Fe 50 compared to using Co 80 Fe 20 .