Influence of image forces on the interlayer exchange interaction in magnetic tunnel junctions with ferroelectric barrier

TL;DR

This paper investigates how image forces influence the voltage-dependent interlayer exchange interaction in magnetic tunnel junctions with ferroelectric barriers, revealing their significant role in the magneto-electric effect and magnetic dynamics.

Contribution

It demonstrates that image forces substantially enhance the magneto-electric effect and can dominate the voltage control of magnetic states in junctions with half-metallic electrodes.

Findings

Image forces significantly enhance the magneto-electric effect.

Image forces can surpass surface charge effects in contribution.

Interlayer exchange coupling variation dominates over spin transfer torque in certain conditions.

Abstract

We study interlayer exchange interaction in magnetic tunnel junctions with ferroelectric barrier. We focus on the influence of image forces on the voltage dependence of the interlayer magnetic interaction (magneto-electric effect). The influence of the image forces is twofold: 1) they significantly enforce magneto-electric effect occurring due to the surface charges at the interface between ferroelectric and ferromagnets; 2) in combination with voltage dependent dielectric constant of the ferroelectric barrier image forces cause an additional contribution to the magneto-electric effect in magnetic tunnel junctions. This contribution can exceed the one coming from surface charges. We compare the interlayer exchange coupling voltage variation with spin transfer torque effect and show that for half-metallic electrodes the interlayer exchange coupling variation is dominant and defines the magnetic state and dynamics of magnetization in the tunnel junction.