Temperature dependence of spin-torque driven ferromagnetic resonance in MgO-based magnetic tunnel junction with a perpendicularly free layer

Highlights: • The spin-torque driven FMR is investigated in MgO MTJ nanopillars with a perpendicularly free layer and an in-plane reference layer. • Both free and reference layers precess at high frequencies in the GHz range under a microwave power. • The saturated magnetization, anisotropy field and damping factor of MgO MTJ have been studied at different temperatures. - Abstract: We report the temperature dependence of the spin-torque (ST) driven ferromagnetic resonance in MgO-based magnetic tunnel junction (MTJ) nanopillars with a perpendicularly free layer and an in-plane reference layer. From the evolution of the resonance frequency with magnetic field, we clearly identify the free-layer resonance mode and reference-layer mode. For the reference layer, we demonstrate a monotonic increase in resonance frequency and the effective damping with decreasing temperature, which suggests the saturated magnetization of the reference layer is dominant. However, for the free layer, the frequency and damping exhibit almost no change with temperature, indicating that the perpendicular magnetic anisotropy plays an important role in magnetization dynamics of the free layer.