Giant magnetoresistance in nanoscale ferromagnetic heterocontacts

TL;DR

This paper develops a quasiclassical theory for giant magnetoresistance in nanoscale ferromagnetic heterocontacts, revealing that magnetoresistance can be both positive and negative depending on the contact configuration.

Contribution

It introduces a model considering different mutual positions of spin subbands and finite contact length, expanding understanding of GMR in heterocontacts.

Findings

Magnetoresistance can be positive or negative in heterocontacts.

The model accounts for finite contact length effects.

Results relate to existing GMR experiments in point heterocontacts.

Abstract

A quasiclassical theory of giant magnetoresistance in nanoscale point contacts between different ferromagnetic metals is developed. The contacts were sorted by three types of mutual positions of the conduction spin-subband bottoms which are shifted one against another by the exchange interaction. A model of linear domain wall has been used to account for the finite contact length. The magnetoresistance is plotted against the size of the nanocontact. In heterocontacts the magnetoresistance effect turned out to be not only negative, as usual, but can be positive as well. Relevance of the results to existing experiments on GMR in point heterocontacts is discussed.