Spin-polarized transport in copper-oxide atomic junctions revealed by anomalous shot-noise behavior in presence of the Kondo effect

TL;DR

This study investigates spin-polarized electron transport in copper-oxide atomic junctions, revealing that these contacts can act as highly efficient spin filters due to local magnetic correlations and Kondo effect-related phenomena.

Contribution

The paper extends the Landauer shot noise model to include energy-dependent transmission and provides experimental evidence of spin filtering in copper-oxide atomic contacts.

Findings

Evidence of local magnetism in copper contacts from hysteretic magnetoresistance and ZBAs.

Anomalous shot noise analysis shows spin polarization can reach full polarization.

Copper oxide atomic contacts exhibit spin-filtering capabilities confirmed by experiments.

Abstract

Noise measurements provide a valuable tool for revealing spin polarization effects in the electronic transport through quantum coherent conductors. We present an extension of the Landauer description of shot noise to include energy-dependent transmission functions and apply it to explore local magnetic correlations in air-oxidized copper contacts, for which first-principle studies have predicted the emergence of ferromagnetic ground states, attributing certain atomic configurations with spin filtering capabilities. By means of low-temperature transport measurements, we provide comprehensive experimental evidence, including hysteretic magnetoresistance and zero-bias anomalies (ZBAs) attributed to the Kondo effect, for the presence of local magnetism. The analysis of the anomalous shot noise in the presence of ZBAs allows us to determine the spin polarization of the current which may reach even full polarization, confirming the spin-filtering capability of copper oxide atomic contacts.