EPITAXIAL SPIN-ORBIT AND MAGNETIC MATERIALS FOR INTEGRATION ONTO A SEMICONDUCTOR PLATFORM

223 pagesToday’s logic and communication systems are dominated by semiconductor devices that utilize the charge of the electron. Meanwhile, magnetic devices, based on the spin of the electron, have historically served as the backbone fordigital memory storage. In recent times, however, charge-based memories, such as flash and dynamic random access memory (DRAM), have become more commonplace. Over the last few decades, advancements in the field of spintronics, which aims to unify usage of the electron’s charge and spin, have made magnetic memories stay competitive. Nevertheless, several charge- and spin-based memory technologies are in competition, and there is great interest in combining the virtues of both. The spin-orbit torque field-effect transistor (SOTFET) is a recently proposed device that combines the spin-orbit torque (SOT) mechanism for writing magnetic memories with semiconductor transistors that are ubiquitous in logic operation. An SOT-controlled ferromagnet is coupled to a semiconducting transistor channel via the transduction of a magnetoelectric multiferroic. The magnetic device may then access the orders-of-magnitude on/off ratio of transistors, which is greater than any modern magnetic memory technology. The integration also gives the device the potential to combine memory and logic. It’s realization, however, relies on the delicate interplay between the spin-orbit, ferromagnetic,multiferroic, and semiconducting materials that comprise it. In this work, I present an overview of the experimental efforts made towards realizing the SOTFET. I will introduce the concepts and working principles behind the SOTFET and then discuss the material parameters and candidates thatare promising for integration into the device. Each layer of the device is unique, and we show the in-depth advancements we have made in the individual layers, as well as the interactions between the layers, to develop the device. Our research eventually focuses on nitride semiconductors, LuFeO3 multiferroics, several ferromagnetic candidates, and Bi-based spin-orbit materials and result in multiple candidate heterostructures for a prototype device. These efforts lay the foundation for realizing a fully-functional SOTFET device in the future.2024-01-0