Current-induced magnetization control in dipolar-coupled nanomagnet pairs and artificial spin ice

TL;DR

This paper demonstrates how current-induced spin-orbit torques can be used to control magnetization states in dipolar-coupled nanomagnet systems, with implications for programmable magnetic devices and neuromorphic computing.

Contribution

It reveals the angular dependence of switching currents and the influence of dipolar coupling, supported by experimental and micromagnetic modeling, advancing control methods for nanomagnetic systems.

Findings

Switching current varies non-monotonically with angle in isolated nanomagnets.

Dipolar coupling affects switching behavior in artificial spin ice.

Micromagnetic modeling supports experimental observations.

Abstract

Exploiting current-induced spin-orbit torques (SOTs) to manipulate the magnetic state of dipolar-coupled nanomagnet systems with in-plane magnetic anisotropy, such as artificial spin ices, provides a route to local, electrically-programmable control of the magnetization, with relevance for applications including neuromorphic computing. Here, we demonstrate how the orientation of a nanomagnet relative to the direction of an applied electrical current impacts the threshold current density needed for all-electrical magnetization switching, and how dipolar coupling between the nanomagnets influences the switching of interacting pairs and ensembles of nanomagnets. Using a material system designed to generate SOTs in response to electrical currents, we find that the current required to switch the magnetization of isolated nanomagnets varies non-monotonically as the angle between the nanomagnet long axis and the current increases. In small artificial spin ice systems, we observe similar angular dependence of the switching current, which can be used to control the magnetization orientation of specific subsets of nanomagnets. These experimental results are supported by micromagnetic modeling, which illustrates how the various current induced torques can be exploited to control magnetization switching in nanomagnetic systems. These results establish SOT switching as a practical method for programmable manipulation of dipolar nanomagnetic systems.