Spin-dependent transport in a multiferroic tunnel junction: Theory for Co/PbTiO$_{3}$/Co

TL;DR

This paper presents a theoretical study of spin-dependent electronic transport in Co/PbTiO3/Co multiferroic tunnel junctions, revealing large TMR and TER effects, and demonstrating how interface details and doping influence transport properties.

Contribution

It introduces a detailed theoretical model showing how interface electronic structure and doping affect spin-dependent tunneling in multiferroic junctions.

Findings

Large tunnel magnetoresistance (TMR) observed.

Significant tunnel electroresistance (TER) demonstrated.

Doping with Zr enhances TMR and alters barrier properties.

Abstract

Spin-dependent electronic transport through multiferroic Co/PbTiO$_{3}$/Co tunnel junctions is studied theoretically. Conductances calculated within the Landauer-B\"uttiker formalism yield both a large tunnel magnetoresistance (TMR) and a large tunnel electroresistance (TER). On top of this, we establish a four-conductance state. The conductances depend crucially on the details of the electronic structure at the interfaces. In particular, the spin polarization of the tunneling electronic states is affected by the hybridization of orbitals and the associated charge transfer at both interfaces. Digital doping of the PbTiO$_{3}$ barrier with Zr impurities at the TiO$_{2}$/Co$_{2}$ interface significantly enhances the TMR\@. In addition, it removes the metalization of the barrier.