Novel Electronic Properties of Unconventional Superconductors

*技术摘要*本项目将继续进行实验，以显著提高对高温超导体中超导电性的起源和铁基超导体的配对对称性的理解。其目的是研究和理解电子掺杂高T_c超导体的低温正常态性质，并利用这一新知识来影响对所有铜酸盐、空穴和电子掺杂的理解。电子掺杂铜酸盐的研究将通过在环境磁场和高于上临界场的磁场中进行各种输运实验来进行，低至毫克开尔文温度。一些输运实验将在静水压力或应变下进行。铁基超导体的研究将根据几篇理论论文中的建议，通过在SQUID或角结排列中的相敏约瑟夫森隧道实验来尝试。所有这些实验的一个重要目标是了解这两类非常规高T_c材料的超导机制，这是凝聚态物理中一个尚未解决的主要问题。这两个系统的正常态和超导性质的比较有望导致对电子关联在高温超导体中的作用的新的和重要的见解。该项目将支持开展拟议研究所必需的物理、材料科学和测量技术方面的一名博士后研究员的教育。从过去的经验来看，这类研究对从学术界到高科技行业的许多科学职业都是一种极好的培训。*非技术摘要*在一些氧化铜和铁基材料中发现高温超导的原因是凝聚态物理学中最重要的悬而未决的问题之一。这些材料在与能源相关的技术中具有巨大的潜力，例如改进的电机以及发电和输电。了解这些材料中的超导机制是至关重要的，以便发展发现可在室温及以上温度下工作的新超导体的知识。该项目将进行旨在解决这一基本科学问题的实验，这也可能有助于开发有用的技术。这将通过采用先进的传输测量技术、制造新材料的新合成方法和已知材料的改进薄膜版本，以及使用国家实验室设施在极端磁场和温度条件下进行测量来实现。该项目将支持开展拟议研究所必需的物理、材料科学和测量技术方面的一名博士后研究员的教育。从过去的经验来看，这类研究对从学术界到高科技行业的许多科学职业来说都是一种极好的培训。如果能够发现室温超导体，它们将对从能源到通信的许多当前技术产生重大影响。

****Technical Abstract****This project will pursue experiments to significantly advance the understanding of the origin of superconductivity in the high-Tc cuprate superconductors and the pairing symmetry of iron-based superconductors. The goal is to study and understand the low-temperature normal state properties of the electron-doped high-Tc superconductors and to use this new knowledge to impact the understanding of all the cuprates, hole- and electron-doped. The electron-doped cuprate research will be carried out via a variety of transport experiments in ambient magnetic field and in fields above the upper critical field down to milliKelvin temperatures. Some transport experiments will be done under hydrostatic pressure or strain. The iron-based superconductor research will be attempted via phase-sensitive Josephson tunneling experiments in a SQUID or corner junction arrangement, as proposed in several theoretical papers. An important goal of all these experiments is to understand the mechanism of superconductivity in these two classes of unconventional high-Tc materials, a major unsolved problem in condensed matter physics. A comparison of the normal state and superconducting properties of these two systems is expected to lead to new and important insights into the role of electronic correlations in high-Tc superconductors. This project will support the education of one postdoctoral fellow in the physics, materials science and measurement techniques necessary to carry out the proposed research. From past experience, this type of research has shown itself to be an excellent training for many scientific careers from academia to high technology industries.****Non-Technical Abstract****The cause of the high-temperature superconductivity found in some copper oxide and iron-based materials is one of the most important unsolved problems in condensed matter physics. These materials have great potential for use in energy related technologies, such as improved motors and electricity generation and transmission. It is crucial to understand the mechanism of superconductivity in these materials in order to develop the knowledge to discover new superconductors that will work at room temperature and above. This project will pursue experiments designed to solve this basic scientific question, and which may also help to develop useful technology. This will be accomplished by employing advanced transport measurement techniques, novel synthetic methods for making new materials and improved thin-film versions of known materials, and by using national laboratory facilities for measurements under extreme magnetic field and temperature conditions. This project will support the education of one postdoctoral fellow in the physics, materials science and measurement techniques necessary to carry out the proposed research. From past experience, this type of research has shown itself to be an excellent training for many scientific careers from academia to high technology industries. If room temperature superconductors can be discovered they will have a significant impact on many current technologies, from energy to communication.