Spin Valve Effect Induced By Spin-Orbit Torque Switching

The spin valve effect driven by the magnetic field in sandwich structures stands out as a seminal phenomenon in the emerging field of spintronics, but it has not been realized in low-power-dissipation devices operated via electrical means. Here, we investigate spin-orbit torque switching in a perpendicularly magnetized CoFeB/Mo/CoFeB sandwich, where the spin current generated in the Mo layer flows upward and downward to the ferromagnetically coupled CoFeB layers. When scanning the current, two CoFeB layers can be switched from one anti-parallel state to a parallel state and then to the other antiparallel state, producing an unprecedentedly current-dependent spin valve effect. Such a spin valve effect is sensitive to the additional magnetic field direction due to the small spin torque efficiency and efficiency difference of the two CoFeB layers. The experimental observations are supported by the dynamics simulation based on the Landau-Lifshitz-Gilbert equation. Besides the fundamental interest, our finding would add a different dimension to energy efficient memory devices and sensors. Published under license by AIP Publishing.