Investigation of Materials, Stacks, and Energy-Efficient Switching of Voltage-Controlled Exchange Coupling Perpendicular Magnetic Tunnel Junctions

Voltage-controlled exchange coupling (VCEC) offers an energy-efficient and deterministic mechanism for manipulating/switching magnetization. This has been recently showcased across multiple perpendicular magnetic tunnel junction (pMTJ) embodiments [1-3]. Despite the marked distinction between the L1₀-textured FePd [1] and the Co/Pd multilayer systems [2,3], these VCEC pMTJ devices share certain essential features. Notably, their special layered structures, particularly the synthetic antiferromagnetic (SAF) free layer, are pivotal for enabling VCEC-switching functionality. This report aims to provide a comprehensive overview of the layered structures in different embodiments, discussing the design of VCEC pMTJ stacks. We also delve into the materials' selection and optimal thickness for each layer. Additionally, we explore potential future research directions and prospects for VCEC pMTJs.

[1] D. Zhang, et al., Nano Lett. 22, 622–629 (2022), DOI: 10.1021/acs.nanolett.1c03395. [2] D. Lyu, et al., Appl. Phys. Lett. 120, 012404 (2022), DOI: 10.1063/5.0075043. [3] B. R. Zink, et al., Adv. Electron. Mater. 8, 2200382 (2022), DOI: 10.1002/aelm.202200382.