The magnetization of ferromagnetic metal can be reversed by spin-orbit torque, a principle used in spintronic devices such as magnetoresistive random access memory. To increase this torque, the injected spins from heavy metals must significantly diffuse into the ferromagnetic metal. However, the thin nature of ferromagnetic metal often leads to the passage of injected spins through it. We analyzed the spin current in a magnetic junction composed of a heavy metal/ferromagnetic metal/non-magnetic layer/ferromagnetic pinned layer/non-magnetic lead. Spin diffusion within the ferromagnetic metal increases with the decreasing conductivity of the non-magnetic material, increasing thickness of the non-magnetic layer, and decreasing thickness of the ferromagnetic pinned layer. These findings are expected to contribute to the advancement of spintronic devices such as spin-orbit torque magnetoresistive random-access memory.Japan Society for the Promotion of Science KAKENHI (Grant Number 20H02607, 23K17765, and 23H01438)departmental bulletin pape
