Micromagnetic understanding of stochastic resonance driven by spin-transfertorque

TL;DR

This paper uses micromagnetic simulations to analyze non-adiabatic stochastic resonance driven by spin-transfer torque in nanomagnets, revealing key dynamics and proposing a microwave detector design.

Contribution

It introduces a micromagnetic simulation approach to understand NASR driven by spin-transfer torque and proposes a new microwave signal detector based on this phenomenon.

Findings

NASR involves thermally activated transitions among static and dynamic states.

The generated voltage at NASR frequency exceeds off-resonance voltage by over an order of magnitude.

Simulation results match experimental features like resonance frequency and temperature dependence.

Abstract

In this paper, we employ micromagnetic simulations to study non-adiabatic stochastic resonance (NASR) excited by spin-transfer torque in a super-paramagnetic free layer nanomagnet of a nanoscale spin valve. We find that NASR dynamics involves thermally activated transitions among two static states and a single dynamic state of the nanomagnet and can be well understood in the framework of Markov chain rate theory. Our simulations show that a direct voltage generated by the spin valve at the NASR frequency is at least one order of magnitude greater than the dc voltage generated off the NASR frequency. Our computations also reproduce the main experimentally observed features of NASR such as the resonance frequency, the temperature dependence and the current bias dependence of the resonance amplitude. We propose a simple design of a microwave signal detector based on NASR driven by spin transfer torque.