3D versus 2D domain wall interaction in ideal and rough nanowires

TL;DR

This study compares the behavior of transverse magnetic domain walls in 2D and 3D nanowires, revealing differences in metastability, interaction, and effects of surface roughness, with implications for domain wall device control.

Contribution

It provides a detailed micromagnetic simulation analysis of 2D and 3D domain wall interactions, highlighting the effects of roughness and artificial constrictions on their dynamics.

Findings

3D TDWs form metastable states with lifetimes around 300ns depending on roughness.

2D TDWs do not form metastable states due to shape anisotropy.

Dipolar interactions in pinned TDWs are accurately modeled by point charge and multipole expansion.

Abstract

The interaction between transverse magnetic domain walls (TDWs) in planar (2D) and cylindrical (3D) nanowires is examined using micromagnetic simulations. We show that in perfect and surface deformed wires the free TDWs behave differently, as the 3D TDWs combine into metastable states with average lifetimes of 300ns depending on roughness, while the 2D TDWs do not due to 2D shape anisotropy. When the 2D and 3D TDWs are pinned at artificial constrictions, they behave similarly as they interact mainly through the dipolar field. This magnetostatic interaction is well described by the point charge model with multipole expansion. In surface deformed wires with artificial constrictions, the interaction becomes more complex as the depinning field decreases and dynamical pinning can lead to local resonances. This can strongly influence the control of TDWs in DW-based devices.