Electric-Field Control of the Interlayer Exchange Coupling for Magnetization Switching

TL;DR

This paper introduces an electric-field-controlled method for magnetization switching using interlayer exchange coupling, leveraging quantum-well formation and resonant tunneling to achieve bias-dependent oscillatory IEC for bi-directional magnetic state control.

Contribution

It presents a novel electric-field mechanism for magnetization switching based on IEC modulation via quantum-well resonant tunneling, reducing current and decoupling switching threshold from speed.

Findings

Bias-dependent oscillatory IEC enables magnetic state switching.

Bi-directional switching achieved with same voltage polarity.

Reduced current and threshold decoupling from switching speed.

Abstract

We propose an electric-field-controlled mechanism for magnetization switching assisted solely by the interlayer-exchange coupling (IEC) between the fixed and the free magnets, which are separated by two oxide barriers sandwiching a spacer material known for exhibiting large IEC. The basic idea relies on the formation of a quantum-well (QW) within the spacer material and controlling the transmission coefficient across the structure with an electric-field via the resonant tunneling phenomena. Using non-equilibrium Green's function (NEGF) method, we show that the structure can exhibit a bias-dependent oscillatory IEC that can switch the free magnet to have either a parallel or an antiparallel configuration with respect to the fixed magnet, depending on the sign of the IEC. Such bi-directional switching can be achieved with the same voltage polarity but different magnitudes. With proper choice of the spacer material, the current in the structure can be significantly reduced. Due to the conservative nature of the exerted torque by the IEC, the switching threshold of the proposed mechanism is decoupled from the switching speed, while the conventional spin-torque devices exhibit a trade-off due to the non-conservative nature of the exerted torque.