Super-giant magnetoresistance at room-temperature in copper nanowires due to magnetic field modulation of potential barrier heights at nanowire-contact interfaces

TL;DR

This study reports a super-giant negative magnetoresistance in copper nanowires at room temperature, caused by magnetic field-induced modulation of potential barriers at nanowire-contact interfaces due to electron deflection.

Contribution

It demonstrates a novel mechanism of magnetoresistance involving magnetic field modulation of interface potential barriers in copper nanowires.

Findings

Achieved ~10,000,000% negative magnetoresistance at 39 mT

Magnetoresistance results from magnetic field-induced barrier height changes

Potential barriers at Cu/Au interfaces are key to the effect

Abstract

We have observed a super-giant (~10,000,000%) negative magnetoresistance at 39 mT field in Cu nanowires contacted with Au contact pads. In these nanowires, potential barriers form at the two Cu/Au interfaces because of Cu oxidation that results in an ultrathin copper oxide layer forming between Cu and Au. Current flows when electrons tunnel through, and/or thermionically emit over, these barriers. A magnetic field applied transverse to the direction of current flow along the wire deflects electrons toward one edge of the wire because of the Lorentz force, causing electron accumulation at that edge and depletion at the other. This lowers the potential barrier at the accumulated edge and raises it at the depleted edge, causing a super-giant magnetoresistance at room temperature.