Domain-wall induced large magnetoresistance effects at zero applied field in ballistic nanocontacts

TL;DR

This study investigates large magnetoresistance effects caused by domain walls in ballistic permalloy nanocontacts, revealing significant MR ratios and sign changes at zero field, supported by atomistic calculations.

Contribution

It demonstrates the occurrence of large, sign-changing magnetoresistance effects at zero field in ballistic nanocontacts, emphasizing atomic configuration's role.

Findings

MR ratio up to 50% observed

Sign change in MR effect detected

Results align with atomistic calculations

Abstract

We determine magnetoresistance effects in stable and clean permalloy nanocontacts of variable cross-section, fabricated by UHV deposition and in-situ electromigration. To ascertain the magnetoresistance (MR) effects originating from a magnetic domain wall, we measure the resistance values with and without such a wall at zero applied field. In the ballistic transport regime, the MR ratio reaches up to 50% and exhibits a previously unobserved sign change. Our results can be reproduced by recent atomistic calculations for different atomic configurations of the nanocontact, highlighting the importance of the detailed atomic arrangement for the MR effect.