Tunneling in double barrier junctions with 'hot spots'

TL;DR

This paper studies electronic transport in double magnetic tunnel junctions with hot spots, revealing quantum well states and resistance oscillations caused by soft barrier breakdown and nitrogen doping.

Contribution

It introduces a model explaining quantum well state formation and resistance oscillations in hot spot regions of double barrier magnetic tunnel junctions.

Findings

Observation of quasi-periodic resistance changes with bias voltage.

Detection of room-temperature oscillations in magnetic configurations.

Identification of quantum well states in the middle Fe layer.

Abstract

We investigate electronic transport in epitaxial Fe(100)/MgO/Fe/MgO/Fe double magnetic tunnel junctions with soft barrier breakdown (hot spots). Specificity of these junctions are continious middle layer and Nitrogen doping of the MgO barriers which provides soft breakdown at biases about 0.5V. In the junctions with hot spots we observe quasi-periodic changes in the resistance as a function of bias voltage which point out formation of quantum well states in the middle Fe continuous free layer. The room-temperature oscillations have been observed in both parallel and antiparallel magnetic configurations and for both bias polarizations. A simple model of tunneling through hot spots in the double barrier magnetic junction is proposed to explain qualitatively this effect.