Giant Voltage Manipulation of MgO-based Magnetic Tunnel Junctions via Localized Anisotropic Strain: a Potential Pathway to Ultra-Energy-Efficient Memory Technology

TL;DR

This paper demonstrates giant voltage control of MgO-based magnetic tunnel junctions using localized anisotropic strain on a piezoelectric substrate, offering a scalable approach for ultra-energy-efficient spintronic memory devices.

Contribution

It introduces a scalable local gating scheme to generate anisotropic strain for controlling MgO MTJs, enhancing their potential for practical, energy-efficient MRAM applications.

Findings

Voltage can efficiently control magnetic properties and TMR in MgO MTJs.

Repeatable toggling between resistance states achieved via strain manipulation.

Crystalline MgO-based MTJs on piezoelectric layers exhibit high TMR.

Abstract

Strain-mediated voltage control of magnetization in piezoelectric/ferromagnetic systems is a promising mechanism to implement energy-efficient spintronic memory devices. Here, we demonstrate giant voltage manipulation of MgO magnetic tunnel junctions (MTJ) on a Pb(Mg1/3Nb2/3)0.7Ti0.3O3 (PMN-PT) piezoelectric substrate with (001) orientation. It is found that the magnetic easy axis, switching field, and the tunnel magnetoresistance (TMR) of the MTJ can be efficiently controlled by strain from the underlying piezoelectric layer upon the application of a gate voltage. Repeatable voltage controlled MTJ toggling between high/low-resistance states is demonstrated. More importantly, instead of relying on the intrinsic anisotropy of the piezoelectric substrate to generate the required strain, we utilize anisotropic strain produced using local gating scheme, which is scalable and amenable to practical memory applications. Additionally, the adoption of crystalline MgO-based MTJ on piezoelectric layer lends itself to high TMR in the strain-mediated MRAM devices.