Switching field reduction of a perpendicular magnetic nanodot in a microwave magnetic field emitted from a spin-torque oscillator

Abstract

We demonstrate microwave-assisted magnetization switching of a perpendicular magnetic nanodot in a microwave stray field from a spin-torque oscillator (STO). The switching field decreases when the STO is operated by applying a current. The switching field reduction is almost the same as that in a microwave magnetic field generated by a signal generator despite the fluctuations of the STO oscillation. The switching field distribution, however, is broader when the STO is used. We also examine the magnetization switching process in the nanosecond region by applying a nanosecond-order pulse current to the STO and measuring the STO signal waveform. The onset of the STO oscillation and subsequent assisted switching occur within a few nanoseconds.