Engineering Interfaces for High-Performance Oxide Superconductor Nanocomposite Films

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NON-TECHNICAL DESCRIPTION: Superconductors are materials that can carry electric currents without loss, which is one of the most exotic physical phenomena in nature and is described quantitatively by the superconducting critical current density Jc. Therefore, superconductivity offers applications such as quantum computing to meet future computing needs and restoring the reliability of the power grid alongside increasing its capacity and efficiency. The discovery of oxide high temperature superconductors (HTSs) provides possibilities for superconductors in applications at liquid nitrogen temperature and presents a fascinating research topic due to their unusual electronic structure and layered crystalline structures which gives profound effects on their physical properties, especially Jc. Raising Jc in HTSs has been the focus of world-wide efforts in the field of applied superconductivity. Growth of nanoscale artificial pinning centers (APCs) provides a powerful approach to raise Jc in nanocomposites, and the method can be directly implemented to large-scale HTS devices for commercialization. This project investigates the strained interfaces, the key driving force in strain-mediated self-assembly of APCs and the determining factor of the APC's pinning efficiency and hence Jc in nanocomposites. The goal is to achieve controllable APCs with precisely designed morphology, orientation, density, and interfaces. The scientific knowledge developed through this project will broadly impact future electronic and electrical applications. Nanoscale control of interfaces applies to computing, sensing, catalysis, and energy production/storage. The integrated modeling-synthesis-characterization approach can be extended to a range of nanocomposites beyond HTSs including ferroelectric, multiferroic, magnetoelectrics and semiconductors to produce novel and unprecedented properties. Both undergraduate and graduate students are gaining the cutting-edge research experience in preparation for careers in science and engineering. Students, especially those from underrepresented groups, are recruited through on campus programs (such as Research Experiences for Undergraduates (REU) Site and APS Bridge programs), collaborators and alumni. TECHNICAL DETAILS: This project focuses on understanding and manipulating interface strains towards controllable growth and high pinning efficiency of nanoscale artificial pinning centers (APCs) in REBa2Cu3O7 (RE-123, RE for rare earth elements Y, Gd, Sm, etc.), aiming at high critical current density (Jc) in a strong magnetic field (H) in the APC/RE-123 nanocomposites. The project has four topics. Topic 1 investigates the pinning efficiency of c-axis aligned one dimensional (1D) APCs, especially the effect of the strained interfaces on Jc and pinning force density Fp. Topic 2 explores schemes, particularly multilayered 1D nanocomposites by insertion of the Ca-substituted RE-123 spacers, for repairing the defective interfaces for enhanced pinning efficiency. Based on theoretical predictions, topic 3 searches for new 1D APCs with small diameters approaching the coherence length and self-repairing functionality. Topic 4 explores APCs of mixed morphologies for H-orientation independent Jc using microscopic control of the strain field in nanocomposites.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.