Role of spin-transfer torques on synchronization and resonance phenomena in stochastic magnetic oscillators

TL;DR

This paper investigates how spin-transfer torques influence synchronization and resonance in stochastic magnetic oscillators, revealing their roles in enhancing response efficiency and potential for low-power applications.

Contribution

It provides a theoretical analysis of the effects of damping-like and field-like torques on stochastic resonance and synchronization in superparamagnetic tunnel junctions.

Findings

Field-like torque enhances forcing efficiency at sub-threshold currents

System response varies significantly between low and high frequencies

Synchronization can be noise-enhanced through spin-transfer torques

Abstract

A theoretical study on how synchronization and resonance-like phenomena in superparamagnetic tunnel junctions can be driven by spin-transfer torques is presented. We examine the magnetization of a superparamagnetic free layer that reverses randomly between two well-defined orientations due to thermal fluctuations, acting as a stochastic oscillator. When subject to an external ac forcing this system can present stochastic resonance and noise-enhanced synchronization. We focus on the roles of the mutually perpendicular damping-like and field-like torques, showing that the response of the system is very different at low and high-frequencies. We also demonstrate that the field-like torque can increase the efficiency of the current-driven forcing, specially at sub-threshold electric currents. These results can be useful for possible low-power, more energy efficient, applications.