Non-equilibrium vertex correction: disorder scattering in magnetic tunnel junctions

TL;DR

This paper introduces a first-principles nonequilibrium vertex correction method integrated with NEGF-DFT to accurately model disorder effects in quantum transport, specifically applied to magnetic tunnel junctions with interface roughness.

Contribution

The authors develop and implement a novel NEGF-DFT-NVC formalism to efficiently account for atomistic disorder in quantum transport calculations from first principles.

Findings

Disorder significantly affects nonlinear spin injection.

Disorder impacts tunnel magneto-resistance ratio.

The method enables self-consistent treatment of disorder in nanoelectronic devices.

Abstract

We report a first principles formalism and its numerical implementation for treating quantum transport properties of nanoelectronic devices with atomistic disorder. We developed a nonequilibrium vertex correction (NVC) theory to handle the configurational average of random disorder at the density matrix level so that disorder effects to nonlinear and nonequilibrium quantum transport can be calculated from atomic first principles in a self-consistent and efficient manner. We implemented the NVC into a Keldysh non-equilibrium Green's function (NEGF) based density functional theory (DFT) and applied the NEGF-DFT-NVC formalism to magnetic tunnel junctions with interface roughness disorder. Our results show that disorder has dramatic effects to nonlinear spin injection and tunnel magneto-resistance ratio.