Magnetoresistance of atomic-sized contacts: an ab-initio study

TL;DR

This study uses first-principles calculations to analyze how atomic-scale contacts of different metals exhibit magnetoresistance, highlighting the effects of atomic arrangement and electronic states on conductance and MR ratios.

Contribution

It provides a detailed ab-initio analysis of magnetoresistance in atomic contacts, emphasizing the role of atomic geometry and electronic states in conductance behavior.

Findings

High MR ratios up to 50% due to spin-splitting in Co contacts.

Conductance through s-like states is stable against geometrical variations.

p and d states significantly influence transmission depending on atomic arrangement.

Abstract

The magnetoresistance (MR) effect in metallic atomic-sized contacts is studied theoretically by means of first-principle electronic structure calculations. We consider three-atom chains formed from Co, Cu, Si, and Al atoms suspended between semi-infinite Co leads. We employ the screened Korringa-Kohn-Rostoker Green's function method for the electronic structure calculation and evaluate the conductance in the ballistic limit using the Landauer approach. The conductance through the constrictions reflects the spin-splitting of the Co bands and causes high MR ratios, up to 50%. The influence of the structural changes on the conductance is studied by considering different geometrical arrangements of atoms forming the chains. Our results show that the conductance through s-like states is robust against geometrical changes, whereas the transmission is strongly influenced by the atomic arrangement if p or d states contribute to the current.