Quantum transport modeling of Fe/MgO/Fe magnetic tunnel junction with FeO$_{0.5}$ buffer layer: the effects of correlations

TL;DR

This study uses ab initio simulations to investigate how on-site Coulomb interactions in a FeO$_{0.5}$ buffer layer affect quantum transport and tunnel magnetoresistance in Fe/MgO/Fe magnetic tunnel junctions, revealing electron localization effects.

Contribution

It introduces a detailed ab initio approach incorporating Hubbard U to analyze correlation effects in FeO$_{0.5}$ buffer layers impacting tunneling properties.

Findings

Coulomb repulsion causes a significant decrease in tunnel magnetoresistance.

Electron localization in the buffer layer explains the magnetoresistance drop.

Symmetry reduction in the buffer layer influences transport properties.

Abstract

We report \textit{ab initio} simulations of quantum transport properties of Fe/MgO/Fe trilayer structures with FeO$_{0.5}$ buffer iron oxide layer, where on-site Coulomb interaction is explicitly taken into account by local density approximation + Hubbard \textit{U} approach. We show that on-site Coulomb repulsion in the iron-oxygen layer can cause a dramatic drop of the tunnel magnetoresistance of the system. We present an understanding of microscopic details of this phenomenon, connecting it to localization of the Fermi electrons of particular symmetry, which takes place in the buffer Fe-O layer, when on-site Coulomb repulsion is introduced. We further study the possible influence of the symmetry reduction in the buffer Fe-O layer on the transport properties of the Fe/MgO/Fe interface.