Domain wall pinning and potential landscapes created by constrictions and protrusions in ferromagnetic nanowires

TL;DR

This study investigates how asymmetric constrictions and protrusions in ferromagnetic nanowires create potential landscapes that pin domain walls, with experimental and simulation results showing dependence on trap type and domain wall chirality.

Contribution

It provides the first detailed experimental and simulation analysis of how specific nanowire geometries influence domain wall pinning and potential landscapes.

Findings

Constrictions and protrusions act as pinning centers for domain walls.

Pinning strength depends on trap type and domain wall chirality.

Micromagnetic simulations agree qualitatively with experimental observations.

Abstract

The potential experienced by transverse domain walls (TDWs) in the vicinity of asymmetric constrictions or protrusions in thin Permalloy nanowires is probed using spatially resolved magneto-optical Kerr effect measurements. Both types of traps are found to act as pinning centers for DWs. The strength of pinning is found to depend on the trap type as well as on the chirality of the incoming DW; both types of traps are seen to act either as potential wells or potential barriers, also depending on the chirality of the DW. Micromagnetic simulations have been performed that are in good qualitative agreement with the experimental results.