A Circuit Model for Domain Walls in Ferromagnetic Nanowires: Application to Conductance and Spin Transfer Torques

TL;DR

This paper introduces a circuit model for electron transport in ferromagnetic nanowires with domain walls, enabling calculation of conductance, magnetoresistance, and spin transfer torques, aligning well with experimental data.

Contribution

It presents a novel circuit-based framework to analyze domain wall transport phenomena, including conductance and spin transfer torques, in ferromagnetic nanowires.

Findings

Derived a simple formula for domain wall magnetoresistance.

Calculated spin transfer torque and estimated domain wall velocity.

Validated model results with recent experimental observations.

Abstract

We present a circuit model to describe the electron transport through a domain wall in a ferromagnetic nanowire. The domain wall is treated as a coherent 4-terminal device with incoming and outgoing channels of spin up and down and the spin-dependent scattering in the vicinity of the wall is modelled using classical resistances. We derive the conductance of the circuit in terms of general conductance parameters for a domain wall. We then calculate these conductance parameters for the case of ballistic transport through the domain wall, and obtain a simple formula for the domain wall magnetoresistance which gives a result consistent with recent experiments. The spin transfer torque exerted on a domain wall by a spin-polarized current is calculated using the circuit model and an estimate of the speed of the resulting wall motion is made.