Stochastic resonance of a nanomagnet excited by spin transfer torque

Abstract

Spin transfer torque from spin-polarized electrical current can excite large-amplitude magnetization dynamics in metallic ferromagnets of nanoscale dimensions. Since magnetic anisotropy energies of nanomagnets are comparable to the thermal energy scale, temperature can have a profound effect on the dynamics of a nanomagnet driven by spin transfer torque. Here we report the observation of unusual types of microwave-frequency nonlinear magnetization dynamics co-excited by alternating spin transfer torque and thermal fluctuations. In these dynamics, temperature amplifies the amplitude of GHz-range precession of magnetization and enables excitation of highly nonlinear dynamical states of magnetization by weak alternating spin transfer torque. We explain these thermally activated dynamics in terms of non-adiabatic stochastic resonance of magnetization driven by spin transfer torque. This type of magnetic stochastic resonance may find use in sensitive nanometer-scale microwave signal detectors.

16 pages, 4 figures

References in corpus (5)

• Spin-transfer-driven ferromagnetic resonance of individual nanomagnets
• Spin-torque switching: Fokker-Planck rate calculation
• Chaotic Dynamics of Spin-Valve Oscillators
• Finite size effects on spin-torque driven ferromagnetic resonance in spin-valves with a Co/Ni synthetic free layer
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• Rectification in Spin-Orbit Materials Using Low Energy Barrier Magnets
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• Optimal Control of Stochastic Magnetization Dynamics by Spin Current
• A CMOS-compatible, scalable and compact magnetoelectric spin-torque microwave detector
• Spin-transfer torque effects in the dynamic forced response of the magnetization of nanoscale ferromagnets in superimposed ac and dc bias fields in the presence of thermal agitation