Domain wall pinning and interaction in rough cylindrical nanowires

TL;DR

This study investigates how surface roughness and radial constrictions in cylindrical nanowires influence magnetic domain wall pinning, interaction, and depinning fields, revealing asymmetries and bound states induced by surface features.

Contribution

It provides new insights into the effects of surface roughness and geometric constrictions on domain wall behavior in cylindrical nanowires, including pinning potential asymmetries and bound state formation.

Findings

Radial constrictions create symmetric pinning potential wells.

Surface roughness decreases depinning fields.

Bound domain wall states are facilitated by surface roughness.

Abstract

Interactions between pairs of magnetic domain walls (DW) and pinning by radial constrictions were studied in cylindrical nanowires with surface roughness. It was found that a radial constriction creates a symmetric pinning potential well, with a change of slope when the DW is situated outside the notch. Surface deformation induces an asymmetry in the pinning potential as well as dynamical pinning. The depinning fields of the domain walls were found generally to decrease with increasing surface roughness. A DW pinned at a radial constriction creates a pinning potential well for a free DW in a parallel wire. We determined that trapped bound DW states appear above the depinning threshold and that the surface roughness facilitates the trapped bound DW states in parallel wires.