Novel Structures, Materials, and Switching Mechanisms of Advanced Perpendicular Magnetic Tunnel Junctions

Abstract

Magnetic tunnel junctions (MTJ), especially those exhibiting perpendicular magnetic anisotropy (PMA), have been the cornerstone for the spintronics community in both academia and industry. Over the past decade or so, significant efforts have been devoted to developing innovative approaches for high-performance PMA-MTJ-based spintronics devices that could support the next-generation memory and computing systems. Starting with an introduction to the fundamentals of MTJ, including the advantages of PMA-MTJs over their in-plane magnetized counterparts, this Dissertation encompasses the experimental investigation of multiple novel structures, materials, and switching mechanisms of nanoscale PMA-MTJ devices. Outstanding performance characteristics such as sub-ns switching speeds, low-temperature functionality down to 2 K, a high voltage-controlled magnetic anisotropy coefficient, and the material compatibility between L10-FePd and Si/SiO2 wafers, have been successfully achieved. Moreover, several new functions of PMA-MTJ, including voltage-controlled exchange coupling and reliable electrical control of the switching layer, are reported. This Dissertation concludes with a summary and an outlook on ongoing projects related to PMA-MTJ. This work could set the stage for future research and engineering efforts, combining these traits to meet performance requirements, advancing the field of emerging memory and logic technologies, and ultimately paving the way for a future where spintronics significantly shapes daily human life.