Electromigration in multiterminal YBCO devices

• Grant number: 25/03723-0
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate (Direct)
• Start date: August 18, 2025
• End date: August 17, 2026
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: Maycon Motta
• Grantee: Caio Cesar Quaglio Gomes
• Supervisor: Alejandro Vladimiro Silhanek
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil
• Institution abroad: Université de Liège (ULg), Belgium
• Associated to the scholarship: 23/11915-1 - Electromigration in YBCO superconducting nanostructures, BP.DD

Abstract

Multiterminal superconducting devices exhibit key properties relevant to technological applications including sensors, interference filters, superconducting electronics, and quantum bits (transmons). In these devices, the presence of multiple voltage and current probes enables local measurement of electrical responses, injection of quasiparticles, and gating, among other functionalities. In particular, previous studies have shown that in niobium-based multiterminal devices, superconducting properties can be selectively modified by applying electrical current, inducing a local electroannealing (EA) effect. This process influences the crystallinity of the metal and, as a result, its superconducting critical temperature. The localized suppression of superconductivity can lead to the formation of a weak-link, effectively transforming the device into a Josephson junction. In more complex superconductors, such as YBa2Cu3O7-d (YBCO), a high-Tc cuprate, electrical current has been used to locally tune the oxygen vacancy concentration through electromigration (EM)-the atomic diffusion driven by high current densities. Since the microstructural and superconducting properties of YBCO are highly sensitive to oxygen content, this approach offers a direct means to explore its rich phase diagram and tune its superconducting properties. This internship project aims to investigate the electromigration in three- and four-terminal YBCO devices, to create and control weak-links in selected regions via electrical current. The host research group has well-established expertise in the EA and EM of metallic and cuprate superconductors, as well as extensive experience with various device geometries at low-dimensional scales. These studies are expected to enhance our understanding of EM-driven modifications in YBCO and contribute to the development of new strategies for superconducting device applications.