Spin-torque oscillators (STOs) exploit the spin-transfer torque effect: a spin-polarized current exerts torque on a magnetic free layer, overcoming damping and driving sustained precession.
The Landau-Lifshitz-Gilbert-Slonczewski equation governs the magnetization unit vector m:
dm/dt = -γm×H_eff + α(m×dm/dt) + τ_STT
Above a critical current, the spin torque compensates damping → self-sustained oscillation at GHz frequencies. Used in microwave nano-oscillators and neuromorphic computing.