Magnetic tunnel junctions with ferroelectric barriers: Prediction of four resistance states from first-principles

TL;DR

This paper predicts four distinct resistance states in multiferroic tunnel junctions with ferroelectric barriers using first-principles calculations, highlighting their potential for advanced spintronic applications.

Contribution

The study demonstrates, through first-principles calculations, the existence of four resistance states in asymmetric SrRuO3/BaTiO3/SrRuO3 MFTJs, advancing the understanding of multiferroic tunnel junctions.

Findings

Resistance significantly changes with polarization reversal.

Resistance varies with electrode magnetization switching.

Four resistance states are achievable in the studied MFTJs.

Abstract

Magnetic tunnel junctions (MTJs), composed of two ferromagnetic electrodes separated by a thin insulating barrier layer, are currently used in spintronic devices, such as magnetic sensors and magnetic random access memories. Recently, driven by demonstrations of ferroelectricity at the nanoscale, thin-film ferroelectric barriers were proposed to extend the functionality of MTJs. Due to the sensitivity of conductance to the magnetization alignment of the electrodes (tunnelling magnetoresistance) and the polarization orientation in the ferroelectric barrier (tunnelling electroresistance), these multiferroic tunnel junctions (MFTJs) may serve as four-state resistance devices. Based on first-principles calculations we demonstrate four resistance states in SrRuO3/BaTiO3/SrRuO3 MFTJs with asymmetric interfaces. We find that the resistance of such a MFTJ is significantly changed when the electric polarization of the barrier is reversed and/or when the magnetizations of the electrodes are switched from parallel to antiparallel. These results reveal the exciting prospects of MFTJs for application as multifunctional spintronic devices.