Effect of resistance feedback on spin torque-induced switching of nanomagnets

TL;DR

This paper investigates how resistance feedback and capacitance influence spin torque-induced magnetization switching in nanomagnets, revealing that feedback can both hinder and enhance switching depending on device type and conditions.

Contribution

It introduces a coupled simulation approach solving Landau-Lifshitz-Gilbert and telegrapher's equations to analyze feedback effects on magnetization reversal in spintronic devices.

Findings

Resistance feedback saturates spin torque in spin valves, hindering switching.

Low resistance magnetic tunnel junctions experience enhanced switching due to feedback.

Capacitive shunting affects switching time only in the picofarad range.

Abstract

In large magnetoresistance devices spin torque-induced changes in resistance can produce GHz current and voltage oscillations which can affect magnetization reversal. In addition, capacitive shunting in large resistance devices can further reduce the current, adversely affecting spin torque switching. Here, we simultaneously solve the Landau-Lifshitz-Gilbert equation with spin torque and the transmission line telegrapher's equations to study the effects of resistance feedback and capacitance on magnetization reversal of both spin valves and magnetic tunnel junctions. While for spin valves parallel (P) to anti-parallel (AP) switching is adversely affected by the resistance feedback due to saturation of the spin torque, in low resistance magnetic tunnel junctions P-AP switching is enhanced. We study the effect of resistance feedback on the switching time of MTJ's, and show that magnetization switching is only affected by capacitive shunting in the pF range.