Perpendicular magnetic tunnel junctions (p-MTJs) switched utilizing bipolar electric fields have extensive applications in energy-efficient memory and logic devices. Voltage-controlled magnetic anisotropy linearly lowers the energy barrier of ferromagnetic layer via electric field effect and efficiently switches p-MTJs only with a unipolar behavior. Here we demonstrate a bipolar electric field effect switching of 100-nm p-MTJs with a synthetic antiferromagnetic free layer through voltage-controlled exchange coupling (VCEC). The switching current density, ~1.1x10^5 A/cm^2, is one order of magnitude lower than that of the best-reported spin-transfer torque devices. Theoretical results suggest that electric field induces a ferromagnetic-antiferromagnetic exchange coupling transition of the synthetic antiferromagnetic free layer and generates a field-like interlayer exchange coupling torque, which cause the bidirectional magnetization switching of p-MTJs. A preliminary benchmarking simulation estimates that VCEC dissipates an order of magnitude lower writing energy compared to spin-transfer torque at the 15-nm technology node. These results could eliminate the major obstacle in the development of spin memory devices beyond their embedded applications.
@article{arxiv.1912.10289,
title = {Bipolar electric field switching of perpendicular magnetic tunnel junctions through voltage controlled exchange coupling},
author = {Delin Zhang and Mukund Bapna and Wei Jiang and Duarte Pereira de Sousa and Yu-Ching Liao and Zhengyang Zhao and Yang Lv and Protyush Sahu and Deyuan Lyu and Azad Naeemi and Tony Low and Sara A Majetich and Jian-Ping Wang},
journal= {arXiv preprint arXiv:1912.10289},
year = {2021}
}