Voltage-controlled interlayer coupling in perpendicularly magnetized magnetic tunnel junctions

T Newhouse-Illige,D Reifsnyder Hickey,X Wang,A Kundu,Chong Bi,K A Mkhoyan,J W Freeland,X M Cheng,C J Sun,Yaohua Liu,D J Keavney,M Xu,W G Wang,Y H Xu,Shufeng Zhang,M Rosales,H Almasi

doi:10.1038/ncomms15232

Abstract

Magnetic interlayer coupling is one of the central phenomena in spintronics. It has been predicted that the sign of interlayer coupling can be manipulated by electric fields, instead of electric currents, thereby offering a promising low energy magnetization switching mechanism. Here we present the experimental demonstration of voltage-controlled interlayer coupling in a new perpendicular magnetic tunnel junction system with a GdOx tunnel barrier, where a large perpendicular magnetic anisotropy and a sizable tunnelling magnetoresistance have been achieved at room temperature. Owing to the interfacial nature of the magnetism, the ability to move oxygen vacancies within the barrier, and a large proximity-induced magnetization of GdOx, both the magnitude and the sign of the interlayer coupling in these junctions can be directly controlled by voltage. These results pave a new path towards achieving energy-efficient magnetization switching by controlling interlayer coupling.

Highlights

Magnetic interlayer coupling is one of the central phenomena in spintronics
In magnetic tunnel junctions (MTJs) with perpendicular easy axes, a switching energy that is more than 10 times smaller than that of spin transfer torques has been demonstrated with the voltage-controlled magnetic anisotropy (VCMA) effect[13,14,15,16,17]
Other voltage-based switching scenarios involving multiferroic or magnetoelectric materials have been intensively investigated[12,19,20,21,22], the incorporation of these materials into an MTJ structure working at room temperature (RT) has yet to be demonstrated