Bipolar spin Hall nano-oscillators

Abstract

We demonstrate a novel type of spin Hall nano-oscillator (SHNO) that allows for efficient tuning of magnetic auto-oscillations over an extended range of gigahertz frequencies, using bipolar direct currents at constant magnetic fields. This is achieved by stacking two distinct ferromagnetic layers with a platinum interlayer. In this device, the orientation of the spin polarised electrons accumulated at the top and bottom interfaces of the platinum layer is switched upon changing the polarity of the direct current. As a result, the effective anti-damping required to drive large amplitude auto-oscillations can appear either at the top or bottom magnetic layer. Tuning of the auto-oscillation frequencies by several gigahertz can be obtained by combining two materials with sufficiently different saturation magnetization. Here we show that the combination of NiFe and CoFeB can result in 3 GHz shifts in the auto-oscillation frequencies. Bipolar SHNOs as such may bring enhanced synchronisation capabilities to neuromorphic computing applications.

References in corpus (7)

• Spin Hall effect
• Magnetic oscillations driven by the spin Hall effect in 3-terminal magnetic tunnel junction devices
• On the origin of magnetization auto-oscillations in constriction-based spin Hall nano-oscillators
• Bridging magnonics and spin-orbitronics
• Domain wall-based spin-Hall nano-oscillators
• Combined frequency and time domain measurements on injection-locked, constriction-based spin Hall nano-oscillators
• Free-standing and positionable microwave antenna device for magneto-optical spectroscopy experiments

Cited by in corpus (6)

• Energy-efficient W${}_{\text{100-x}}$Ta${}_{\text{x}}$/CoFeB/MgO spin Hall nano-oscillators
• Field-free high-frequency exchange-spring spin-torque nano-oscillators
• Easy-plane spin Hall oscillator
• Parametric resonance of spin waves in ferromagnetic nanowires tuned by spin Hall torque
• Spin orbit torque nano-oscillators by dipole field-localized spin wave modes
• Mutual synchronization in spin torque and spin Hall nano-oscillators