Geometrically constrained magnetic wall

TL;DR

This paper introduces a new type of magnetic wall constrained by geometry, which differs significantly from traditional walls and explains large magnetoresistance in atomic point contacts.

Contribution

It presents a theoretical analysis of geometrically constrained magnetic walls, revealing their unique properties and potential to explain observed magnetoresistance phenomena.

Findings

Constrained magnetic walls are significantly narrower than unconstrained ones.

The width of the constrained wall decreases with smaller constriction characteristic length.

This explains the large magnetoresistance in ferromagnetic atomic point contacts.

Abstract

The structure and properties of a geometrically constrained magnetic wall in a constriction separating two wider regions are investigated theoretically. They are shown to differconsiderably from those of an unconstrained wall, so that the geometrically constrained magnetic wall truly constitutes a new kind of magnetic wall, besides the well known Bloch and Neel walls. In particular, the width of a constrained wall cann become very small if the characteristic length of the constriction is small, as is actually the case in an atomic point contact. This provides a simple, natural explanation for the large magnetoresistance observed in ferromagnetic atomic point contacts.