Non-equilibrium Green's function based single-band tight-binding model for Fe-MgO-Fe magnetic tunnel junction devices

TL;DR

This paper presents a theoretical single-band tight-binding model using non-equilibrium Green's functions to accurately predict the voltage-dependent TMR in Fe-MgO-Fe magnetic tunnel junctions, aligning well with experimental data.

Contribution

It introduces a simplified yet effective model capturing key electronic and transport properties of Fe-MgO-Fe junctions, matching ab-initio and experimental results.

Findings

Quantitative voltage dependence of TMR captured

Model trends agree with ab-initio predictions

Effective description of spin-dependent transport

Abstract

Motivated by observation of very high tunnel magnetoresistance (TMR) in Fe-MgO-Fe magnetic tunnel junction devices, we propose a theoretical model for these devices based on a single-band tight-binding approximation. An effort is made to capture the band dispersions over the two dimensional transverse Brillouin zone. In the transport direction, spin dependent Hamiltonian is prescribed for Delta_1 and Delta_5 bands. Non-equilibrium Green's function formalism is then used to calculate transport. Features like voltage dependence of TMR are captured quantitatively within this simple model and the trends match well with the ones predicted by ab-initio methods and experiments.