Nonlocal Electrodynamics Effect and Microscopic Intrinsic Parameters in Pippard Superconductors. Experimental Study

皮帕德超导体中的非局域电动力学效应和微观本征参数。

• 批准号: 0904157
• 负责人: Vladimir Kozhevnikov
• 金额: $ 19万
• 依托单位: Tulsa Community College
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-12-01 至 2015-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0904157&HistoricalAwards=false
• 关键词: Nonlocal; Electrodynamics; Effect; Microscopic; Intrinsic

****NON-TECHNICAL ABSTRACT****Superconductivity is one of the most striking phenomena of consequence for scientific understanding and applications. Discovered nearly one hundred years ago, it took scientists more than four decades to achieve a general understanding of this phenomenon. Soon after, practical applications of superconductivity began emerging. Probably, the most well-known of those is Magnetic Resonance Imaging. Since 1986 physicists have faced a new challenge, the discovery of unconventional superconductors, which defied conventional understanding. The basic concept of superconductivity theory is the formation of Cooper pairs, ?quasiparticles? consisting of two-electrons that transport current without resistance (a supercurrent). The dimension of a Cooper pair is of the order of a thousand atomic sizes and a pair?s mass is about 2.5 times that of an electron. Knowledge of these parameters is important both for the theory and for practical applications. Surprisingly enough, experimental values of these key characteristics have not yet been experimentally established for any superconductor. This individual investigator award supports a project which goal is to measure the size and the mass of the Cooper pairs in conventional superconductors. The experiments will be performed using the most advanced nuclear techniques of condensed matter physics. Direct involvement of community college students constitutes a major educational merit of this project. ****TECHNICAL ABSTRACT****The principal microscopic intrinsic parameters of superconductors, important for both superconductivity theory and for practical applications, are the London penetration depth at zero temperature and the Pippard coherence length. To date the experimental values of these parameters have not been established for any superconductor. This individual investigator award supports a project to directly measure the London penetration depth and the Pippard coherence length in classical Pippard (extreme Type-I) superconductors, specifically in Al, In and Sn. Taking into account that the Pippard coherence length represents the size of the Cooper pairs and the London penetration depth is associated with the mass of the quasiparticles, the project is targeted at obtaining experimental values of these key characteristics of the Cooper pairs for the indicated materials. Values of the microscopic intrinsic parameters will be obtained from the profile of the magnetic field penetrating into the superconductors in the Meissner state. The magnetic field profiles will be measured using polarized neutron reflectometry, low-energy muon spin rotation spectroscopy and beta-detected NMR techniques. Direct involvement of community college students constitutes a major educational merit of this project.

* 非技术性摘要 * 超导性是科学理解和应用中最引人注目的现象之一。发现于近一百年前，科学家们花了四十多年的时间才对这一现象有了大致的了解。不久之后，超导的实际应用开始出现。其中最著名的可能是磁共振成像。自1986年以来，物理学家面临着一个新的挑战，即发现非传统超导体，这违背了传统的理解。超导理论的基本概念是库珀对的形成，？准粒子？由两个电子组成，可以无电阻地传输电流（超电流）。库珀对的尺寸是一千个原子大小的数量级，而一对？的质量大约是电子的2.5倍，这些参数的知识对于理论和实际应用都是很重要的。令人惊讶的是，这些关键特性的实验值还没有在任何超导体的实验中建立起来。这项个人研究奖支持一个项目，其目标是测量传统超导体中库珀对的大小和质量。实验将使用凝聚态物理学中最先进的核技术进行。社区大学生的直接参与构成了该项目的主要教育优点。* 技术摘要 * 对于超导理论和实际应用都很重要的超导体的主要微观本征参数是零温下的伦敦穿透深度和皮帕德相干长度。到目前为止，这些参数的实验值还没有建立任何超导体。这个个人研究奖支持一个项目，以直接测量伦敦渗透深度和Pippard相干长度在经典Pippard（极端I型）超导体，特别是在铝，铟和锡。考虑到皮帕德相干长度代表库珀对的大小，伦敦穿透深度与准粒子的质量有关，该项目的目标是获得所示材料的库珀对的这些关键特性的实验值。微观内禀参数的值将从穿透迈斯纳态超导体的磁场分布中获得。将使用极化中子反射计、低能μ子自旋旋转光谱学和β探测核磁共振技术测量磁场分布。社区大学生的直接参与构成了该项目的主要教育优点。