Analysis of the current-driven domain wall motion in a ratchet ferromagnetic strip

TL;DR

This paper investigates current-driven domain wall motion in a ratchet ferromagnetic strip using micromagnetic simulations and a modified one-dimensional model, highlighting the importance of anisotropy energy and pulse timing for device performance.

Contribution

It introduces a new term in the q-Φ equations accounting for anisotropy energy, improving the predictive power of the model for ratchet memory behavior.

Findings

The one-dimensional model accurately predicts domain wall motion.

Proper pulse timing is crucial for device operation.

Current-driven regime offers advantages over field-driven regime.

Abstract

The current-driven domain wall motion in a ratchet memory due to spin-orbit torques is studied from both full micromagnetic simulations and the one dimensional model. Within the framework of this model, the integration of the anisotropy energy contribution leads to a new term in the well known q-$\Phi$ equations, being this contribution responsible for driving the domain wall to an equilibrium position. The comparison between the results drawn by the one dimensional model and full micromagnetic simulations proves the utility of such a model in order to predict the current-driven domain wall motion in the ratchet memory. Additionally, since current pulses are applied, the paper shows how the proper working of such a device requires the adequate balance of excitation and relaxation times, being the latter longer than the former. Finally, the current-driven regime of a ratchet memory is compared to the field-driven regime described elsewhere, then highlighting the advantages of this current-driven regime.

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