Phase-Sensitive Probes of Unconventional Superconductors and pi-Josephson junctions

这个项目解决了凝聚态物理学中最重要和最吸引人的问题之一--“相”和“相相干”在超导体系统中的作用。这些基本性质导致了超导体令人着迷的行为，并导致了超导电子器件的独特潜力和能力。研究人员将探索超导体中新的“相位相干”现象，这为先进的电子设备和深入了解耦合量子系统的内部工作原理提供了独特的机会。这项工作的长期目标之一是了解电子如何相互作用，以产生奇异材料中的非传统超导电性，这种材料表现出磁性和超导电性的共存。最终，这可能会导致发现具有更高的转变温度和更好的电子性能的超导材料。第二个目标是了解混合超导体-磁性设备中的电荷传输，这些设备有可能成为先进数字电子、灵敏模拟探测器以及量子信息处理和量子计算应用方案的构建块。除了技术转让的潜力，这里概述的项目将为材料和器件物理方面的新兴学生研究人员提供培训基础，并通过研究团队的组成，加强未被充分代表的人口群体对尖端科学研究的参与。*技术摘要*本项目将探索非传统超导材料和器件中的相和相干性的作用。超导序参数的位相决定了超导体的迷人性质，并导致了超导电子器件的独特潜力和能力。研究人员将进行一系列实验，旨在研究超导体中的相位相干现象。相敏测试将确定被怀疑表现出非传统配对对称性的奇异超导材料的配对对称性，包括新发现的表现出磁性和超导电性共存的材料。这项工作的长期目标是了解对称性如何与微观配对相互作用有关。最终，这项研究可能导致具有更高的转变温度、更高的临界电流和更好的高频性能的超导材料。另一项工作将探索pi-Josephson结的相结构和相动力学，其特征是基态pi的相位下降。这些结将包括表现出各种序参数对称性的非传统超导体，或者具有以相关相为特征的隧道势垒，如铁磁体、反铁磁体、纳米管、石墨烯片或被驱动进入非平衡状态的正常金属。这些设备为深入了解耦合量子系统的内部工作原理、先进的数字电子学、灵敏的模拟探测器以及量子信息处理和量子计算应用提供了独特的机会。除了技术转让的潜力，这里概述的项目将为新出现的学生研究人员提供培训场所，并通过研究团队的组成，加强未被充分代表的人口群体对尖端科学研究的参与。

NON-TECHNICAL ABSTRACTThis 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.