Giant Positive Magnetoresistance in Co@CoO Nanoparticle Arrays

TL;DR

This study investigates the magnetotransport properties of Co@CoO nanoparticle arrays, revealing a giant positive magnetoresistance exceeding 1,400% at 10K, explained by Zeeman splitting effects on localized states.

Contribution

It provides the first detailed analysis of giant positive magnetoresistance in Co@CoO nanoparticle arrays and explains the phenomenon through Zeeman splitting and Coulomb interactions.

Findings

Giant positive magnetoresistance >1,400% at 10K

Temperature-dependent transition between Efros-Shklovskii VRH and simple activation

Magnetoresistance explained by Zeeman splitting and Coulomb effects

Abstract

We report the magnetotransport properties of self-assembled Co@CoO nanoparticle arrays at temperatures below 100 K. Resistance shows thermally activated behavior that can be fitted by the general expression of R exp{(T/T0)^v}. Efros-Shklovskii variable range hopping (v=1/2) and simple activation (hard gap, v=1) dominate the high and low temperature region, respectively, with a strongly temperature-dependent transition regime in between. A giant positive magnetoresistance of >1,400% is observed at 10K, which decreases with increasing temperature. The positive MR and most of its features can be explained by the Zeeman splitting of the localized states that suppresses the spin dependent hopping paths in the presence of on-site Coulomb repulsion.