NON-TECHNICAL ABSTRACT This project addresses one of the most important and captivating problems in condensed matter physics - the role of the "phase" and "phase coherence" in superconductor systems. These fundamental properties are responsible for the fascinating behavior of superconductors and leads to the unique potential and capabilities of superconductor electronic devices. The investigators will explore novel "phase-coherent" phenomena in superconductors that present unique opportunities for advanced electronic devices and for insights into the inner workings of coupled quantum systems. One long-term goal of this work is to understand how electrons interact with each other to give rise to the unconventional superconductivity in exotic materials that exhibit coexistence of magnetism and superconductivity. Ultimately, this may lead to the discovery of superconducting materials with higher transition temperatures and better electronic performance. A second goal is to understand the charge transport in hybrid superconductor-magnetic devices that have potential as building blocks in schemes for advanced digital electronics, sensitive analog detectors, and quantum information processing and quantum computing applications. Beyond the technology transfer potential, the project outlined here will provide a training ground for emerging student researchers in materials and device physics and, by the composition of the research team, enhance the involvement of underrepresented demographic groups in cutting edge scientific research.
****TECHICAL ABSTRACT**** This project will explore the role of the phase and phase coherence in unconventional superconductor materials and devices. The phase of the superconducting order parameter is responsible for the fascinating properties of superconductors and leads to the unique potential and capabilities of superconductor electronic devices. The investigators will carry out a series of experiments which are designed to study phase-coherent phenomena in superconductors. Phase-sensitive tests will determine the pairing symmetry of exotic superconducting materials suspected to exhibit unconventional pairing symmetry, including newly-discovered materials that exhibit coexistence of magnetism and superconductivity. A longer-term goal of this work is to understand how the symmetry is related to the microscopic pairing interaction. Ultimately, this research may lead to superconducting materials with higher transition temperatures, higher critical currents, and better high frequency performance. Other work will probe the phase structure and phase dynamics of pi-Josephson junctions, which are characterized by a phase drop of pi in the ground state. The junctions will incorporate unconventional superconductors exhibiting various order parameter symmetry, or have tunneling barriers featuring correlated phases such as ferromagnets, antiferromagnets, nanotubes, graphene sheets, or normal metals driven into a non-equilibrium state. Such devices present unique opportunities for insights into the inner workings of coupled quantum systems and for advanced digital electronics, sensitive analog detectors, and quantum information processing and quantum computing applications. Beyond the technology transfer potential, the project outlined here will provide a training ground for emerging student researchers and, by the composition of the research team, enhance the involvement of underrepresented demographic groups in cutting edge scientific research.
