Current-Driven Domain-Wall Dynamics in Curved Ferromagnetic Nanowires

TL;DR

This paper develops an analytical model describing how current-driven domain walls move in curved ferromagnetic nanowires, revealing harmonic oscillation behavior and linking material parameters to dynamical properties.

Contribution

It introduces a micromagnetic-based analytical solution for domain-wall dynamics in curved nanowires, connecting material parameters with oscillation characteristics.

Findings

Analytical solution characterizes domain-wall motion as harmonic oscillation.

Strong curvature affects eigenmodes through dipole moment and geometry.

Numerical calculations confirm the analytical model and highlight its limitations.

Abstract

The current-induced motion of a domain wall in a semicircle nanowire with applied Zeeman field is investigated. Starting from a micromagnetic model we derive an analytical solution which characterizes the domain-wall motion as a harmonic oscillation. This solution relates the micromagnetic material parameters with the dynamical characteristics of a harmonic oscillator, i.e., domain-wall mass, resonance frequency, damping constant, and force acting on the wall. For wires with strong curvature the dipole moment of the wall as well as its geometry influence the eigenmodes of the oscillator. Based on these results we suggest experiments for the determination of material parameters which otherwise are difficult to access. Numerical calculations confirm our analytical solution and show its limitations.