Even-odd effects in magnetoresistance of ferromagnetic domain walls

TL;DR

This paper investigates how the density of states differences in ferromagnets cause oscillating potential discontinuities at domain boundaries, affecting magnetoresistance, and introduces a new type of domain wall with unique properties.

Contribution

It proposes a novel mechanism for magnetoresistance effects based on spin accumulation and introduces a new domain wall type with non-rotating magnetization in nanowires.

Findings

Discontinuities oscillate with the number of domains.

Large magnetoresistance explained by spin accumulation.

New domain walls without magnetization rotation are possible.

Abstract

Difference in density of states for the spin's majority and minority bands in a ferromagnet changes the electrostatic potential along the domains, introducing the discontinuities of the potential at domain boundaries. The value of discontinuity oscillates with number of domains. Discontinuity depends on the positions of domain walls, their motion or collapse of domain walls in applied magnetic field. Large values of magnetoresistance are explained in terms of spin-accumulation. We suggest a new type of domain walls in nanowires of itinerant ferromagnets, in which the magnetization vector changes without rotation. Absence of transverse magnetization components allows considerable spin accumulation assuming the spin relaxation length, L_S, is large enough.