Diode Like Attributes in Magnetic Domain Wall Devices via Geometrical Pinning for Neuromorphic Computing

TL;DR

This paper introduces a novel pine-tree-shaped magnetic domain wall device with asymmetric pinning, demonstrating diode-like behavior for potential use in energy-efficient neuromorphic computing systems.

Contribution

It proposes and experimentally investigates a new device design that exhibits diode-like properties through geometrical pinning, advancing magnetic domain wall devices for neuromorphic applications.

Findings

Successful observation of multiple magnetization states driven by SOT current.

Asymmetric pinning strength observed in DW movement, enabling diode-like behavior.

Micromagnetic simulations support experimental results and guide device design.

Abstract

Neuromorphic computing (NC) is considered as a potential vehicle for implementing energy-efficient artificial intelligence (AI). To realize NC, several materials systems are being investigated. Among them, the spin-orbit torque (SOT) -driven domain wall (DW) devices are one of the potential candidates. To implement these devices as neurons and synapses, the building blocks of NC, researchers have proposed different device designs. However, the experimental realization of DW device-based NC is only at the primeval stage. In this study, we have proposed and investigated pine-tree-shaped DW devices, based on the Laplace force on the elastic DWs, for achieving the synaptic functionalities. We have successfully observed multiple magnetization states when the DW was driven by the SOT current. The key observation is the asymmetric pinning strength of the device when DW moves in two opposite directions (defined as, xhard and xeasy). This shows the potential of these DW devices as DW diodes. We have used micromagnetic simulations to understand the experimental findings and to estimate the Laplace pressure for various design parameters. The study leads to the path of device fabrication, where synaptic properties are achieved with asymmetric pinning potential.