UC Riverside

Superconductors have long attracted both scientific and industrial interest due to their ability to carry electrical current without dissipation and to enable device concepts rooted in macroscopic quantum coherence. Central to many practical limitations and opportunities in superconducting electronics is the behavior of magnetic vortices. Vortex dynamics influence critical current, noise performance, and flux stability in both low temperature superconductors (LTS) and high temperature superconductors (HTS). Studying vortex motion by engineering materials at the nanoscale is therefore essential for superconducting technologies. Superconductors are predominantly divided into two groups based on their operating temperature: low temperature superconductors (LTS), which typically operate near liquid helium temperatures, and high temperature superconductors (HTS), which remain superconducting at significantly higher temperatures. LTS materials such as Nb and NbN possess relatively long coherence lengths, metallic electronic structures, and support robust multilayer fabrication with highly reproducible device performance. High temperature viii cuprate superconductors such as YBCO operate at higher temperatures but exhibit short coherence lengths, complex fabrication requirements, and extreme sensitivity to dis order. While generally complex materials to work with, they also provide an opportunity in which carefully introduced nanoscale disorder can be used to locally tune superconductivity and manipulate material behavior. Focused ion beam (FIB) techniques, particularly helium ion irradiation, provide a maskless and highly controlled method for engineering superconducting properties with nanometer precision. This dissertation investigates FIB modified superconductors as a platform to create devices that take advantage of vortex motion and mitigate it when it is disadvantageous. Chapter 1 provides a brief theoretical overview of superconductivity, including flux quantization, Josephson physics, and vortex electrodynamics. Chapter 2 examines the Josephson diode effect in YBCO thin-films, emphasizing asymmetric vortex motion. Chapter 3 explores the integration of Josephson junctions on YBCO films grown on silicon substrates, advancing compatibility with scalable platforms. Chapter 4 details pulsed laser deposition of YBCO at High Temperature Superconductors Inc. to help establish in house thin film growth capability and enable rapid iteration of film growth. Chapter 5 investigates ion irradiation based modification of thicker YBCO films aimed at enhancing diode performance through increased critical currents. Although creating asymmetric devices was not achieved, the study successfully demonstrates reliable Josephson junction formation in thicker films. Finally, Chapter 6 studies vortex mitigation strategies in Nb and NbN superconducting electronics, addressing flux trapping and nanoscale vortex engineering in low-temperature superconducting platforms.