Inhomogeneity and Charge Modulation in Unconventional Superconductors

非技术摘要量子材料是我们这个日益科技化的世界中新型电子设备的未来。用于核磁共振医学成像的超导体是一项成熟的技术，而用于量子计算的量子比特是一项新兴技术，这是量子材料在我们的社会中已经或将无处不在的两个例子。这项研究是为了更好地了解目前使用的功能量子材料，以便发现下一代量子材料所做的大量努力的一部分。该项目将专注于超导材料，用于核磁共振成像和量子计算。先进的实验技术使用了世界上可用的最高磁场、脉冲功率系统和射频系统，这些技术也可以促进能源、通信和制造等行业的发展。最后，参与这些项目的本科生和研究生被培养成下一代科学家。技术摘要了解量子力学基态对于创造下一代电子器件和发展量子通信是至关重要的。PI的研究通过对显示非均匀超导特征的准二维有机超导体进行系统测量，促进了对量子系统的理解。这种奇异的超导态，是空间调制的超导序参数和未配对电子的磁性晶格的可调混合物，在50多年前被预测，被称为FFLO态。FFLO态可以通过温度、磁场的方向和强度以及压力进行高度可调。这项研究继续使用隧道二极管振荡器对射频穿透深度进行核心测量，并对有机超导体和锂离子超导体的比热进行测量。PI还测量了FFLO态电荷调制的对称性和波长，以及使用X射线的电荷密度波。为了促进这些实验，国际和平研究所正在与阿贡国家实验室的高级光子源以及塔拉哈西和洛斯阿拉莫斯的国家高磁场实验室合作，以升级进入高磁场实验室的途径。在有机和锂离子导体中，阴离子或元素的替代和中等的压力使人们很容易通过超导材料中普遍存在的温度-载流子浓度相图。将系统从密度波绝缘态，通过超导电性，再到金属状态，将提供被认为对超导电性负责的量子临界点的证据。理解基态之间的竞争是量子材料中的一个中心问题，而量子临界点是这个问题的核心。测量、模型计算和广泛的晶体样本库的结合将促进理解量子材料物理的目标。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Non-Technical AbstractQuantum materials are the future of new electronic devices in our increasingly technological world. Superconductors for MRI medical imaging, a mature technology, and qubits for quantum computing, a nascent technology, are two examples of quantum materials that are or will be ubiquitous in our society. This research is part of a large effort to better understand the functional quantum materials used presently so that the next generation of quantum materials can be discovered. This project will focus on superconducting materials, used both in MRI imaging and quantum computing. Advancing experimental techniques that use the highest magnetic fields available in the world, pulsed power systems, and radio frequency systems are some of the technologies that also can advance sectors such as energy, communications, and manufacturing. Finally, the undergraduate, and graduate students who participate in these projects are trained as the next generation of scientists. Technical AbstractUnderstanding quantum mechanical ground states is essential to create the next generation of electronic devices and develop quantum communications. The PI's research is advancing the understanding of quantum systems by making systematic measurements of quasi-two dimensional organic superconductors that show signatures of inhomogeneous superconductivity. This exotic superconducting state, a tunable mixture of a spatially modulated superconducting order parameter and a magnetic lattice of unpaired electrons, was predicted over 50 years ago, and is called the FFLO state. The FFLO state is highly tunable via temperature, the direction and strength of the magnetic field, and pressure. This research continues the core measurements of rf penetration depth using a tunnel diode oscillator and specific heat of organic and pnictide superconductors. The PI also measures the symmetry and wavelength of the charge modulation in the FFLO state and charge density waves using x-rays. To facilitate these experiments the PI is working with the Advanced Photon Source at Argonne National Laboratory (APS) and the National High Magnetic Field Laboratory in Tallahassee and Los Alamos to upgrade access to high magnetic fields at the APS. In organic and pnictide conductors anion or element substitution and moderate pressure make it easy to traverse the temperature-carrier concentration phase diagram that is ubiquitous among superconducting materials. Tuning the system from the density wave insulating state, through superconductivity, and into a metallic state will provide evidence of the quantum critical point thought to be responsible for superconductivity. Understanding the competition between ground states is a central question in quantum materials and the quantum critical point is central to this problem. The combination of measurements, model calculations, and an extensive library of crystal samples will further the goal of understanding the physics of quantum materials.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.