Magnetoresistance through spin polarized p-states

TL;DR

This paper presents a theoretical analysis showing that spin-polarized oxygen p-states in Ni contacts can significantly enhance magnetoresistance, explaining recent experimental observations of large ratios.

Contribution

It introduces a novel mechanism involving spin-polarized oxygen states in magnetoresistance, expanding understanding beyond clean domain wall models.

Findings

Spin-polarized oxygen p-states facilitate electronic transport in Ni contacts.

Presence of oxygen defects can increase magnetoresistance by an order of magnitude.

Mechanism surpasses traditional domain wall-based explanations.

Abstract

We present a theoretical study of the ballistic magnetoresistance in Ni contacts using first-principles, atomistic electronic-structure calculations. In particular we investigate the role of defects in the contact region in order to explain the recently observed spectacular magnetoresistance ratio. Our results predict that possible presence of spin polarized oxygen in the contact region, could explain conductance changes by an order of magnitude. Electronic transport essentially occurs through spin-polarized oxygen p states, and this mechanism gives a much higher magnetoresistance than that obtained assuming clean atomically sharp domain walls alone.