UC San Diego

Magnetic materials and nanoscale devices are at the heart of data storage technologies, from decades-old hard drives to future technologies such as magnetoresistive random access memory or racetrack memory. Driven by the constantly increasing demand for more storage space and performances, the focus has shifted from magnetic field-based applications to spin current-based applications. This thesis discusses some of the challenges faced when studying interactions between electrical currents and magnetic materials. It starts with an introduction to micromagnetics and the description of the main magnetic interactions. It then focuses on racetrack memories and details the advantages of antiferromagnetically coupled nanowires. The next chapters are dedicated to spin-valves, including a study of composite free-layers, the influence of Dzialoshinskii-Moriya interactions on the performance of memory cells, and the forward flux sampling method to predict the switching probability under non-zero temperature. All of these chapters contain work done on the FastMag micromagnetic simulation software, developed in-house. Some general ideas and details on the implementation of magnetic fields and methods for simulation are also provided.