Enhanced magneto-transport at high bias in quasi-magnetic tunnel junctions with EuS spin-filter barriers

TL;DR

This study reports an unusual increase in magnetoresistance at high bias in quasi-magnetic tunnel junctions with EuS barriers, explained by Fowler-Nordheim tunneling through a fully spin-polarized conduction band.

Contribution

It demonstrates high bias magnetoresistance enhancement in QMTJs with EuS barriers and provides theoretical explanation matching experimental data.

Findings

Large magnetoresistance observed in QMTJs with EuS barriers

Abrupt MR increase at high bias voltage

Fowler-Nordheim tunneling explains the behavior

Abstract

In quasi-magnetic tunnel junctions (QMTJs) with a EuS spin filter tunnel barrier between Al and Co electrodes, we observed large magnetoresistance (MR). The bias dependence shows an abrupt increase of MR ratio in high bias voltage, which is contrary to conventional magnetic tunnel junctions (MTJs). This behavior can be understood as due to Fowler-Nordheim tunneling through the fully spin-polarized EuS conduction band. The I-V characteristics and bias dependence of MR calculated using tunneling theory shows excellent agreement with experiment.