The theory of magnetic field induced domain-wall propagation in magnetic nanowires

TL;DR

This paper develops a theoretical framework describing how magnetic domain walls in nanowires propagate under an external magnetic field, linking their motion to energy dissipation and structural oscillations.

Contribution

It provides a comprehensive theoretical model explaining the dynamics of domain wall propagation driven by magnetic fields in nanowires, including energy dissipation and oscillatory behaviors.

Findings

DW cannot be static in a homogeneous nanowire under a magnetic field.

DW speed is proportional to energy dissipation rate.

Oscillatory DW motion causes speed oscillations.

Abstract

A global picture of magnetic domain wall (DW) propagation in a nanowire driven by a magnetic field is obtained: A static DW cannot exist in a homogeneous magnetic nanowire when an external magnetic field is applied. Thus, a DW must vary with time under a static magnetic field. A moving DW must dissipate energy due to the Gilbert damping. As a result, the wire has to release its Zeeman energy through the DW propagation along the field direction. The DW propagation speed is proportional to the energy dissipation rate that is determined by the DW structure. An oscillatory DW motion, either the precession around the wire axis or the breath of DW width, should lead to the speed oscillation.