Analysis Of Measured Transport Properties Of Domain Walls In Magnetic Nanowires And Films

TL;DR

This paper investigates the relationship between domain wall transport properties in magnetic nanowires and films, revealing a universal parameter linking wall mobility to geometric factors and comparing experimental data with theoretical models.

Contribution

It provides experimental analysis of domain wall mobility and its dependence on aspect ratio, validating Berger's 1984 theory over other models.

Findings

Wall mobility scales as (t/w)^{-2.2} in nanowires

Data supports Berger's 1984 s-d exchange theory

Contradicts predictions of Tatara and Kohno, Zhang and Li theories

Abstract

Existing data for soft magnetic materials of critical current for domain-wall motion, wall speed driven by a magnetic field, and wall electrical resistance, show that all three observable properties are related through a single parameter: the wall mobility $\mu$. The reciprocal of $\mu$ represents the strength of viscous friction between domain wall and conduction-electron gas. And $\mu$ is a function of the wall width, which depends in turn on the aspect ratio t/w, where t and w are the thickness and width of the sample. Over four orders of magnitude of $\mu$, the data for nanowires show $\mu\propto (t/w)^{-2.2}$. This dependence is in approximate agreement with the prediction of the 1984 Berger theory based on s-d exchange. On the other hand, it is inconsistent with the prediction of the 2004 Tatara and Kohno theory, and of the 2004 Zhang and Li theory.