Vorticles and Quasiparticles in Superconducting Films in the Small Order Parameter Amplitude Limit

小阶参数振幅极限下超导薄膜中的涡旋和准粒子

• 批准号: 0605797
• 负责人: James Valles
• 金额: --
• 依托单位: Brown University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-07-15 至 2010-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0605797&HistoricalAwards=false
• 关键词: Vorticles; Quasiparticles; Superconducting; Films; Small

Non TechnicalPhysicists can explain why some materials behave as magnets, others as superconductors and others, insulators, do not carry electricity at all. Many technologically promising new materials, however, exhibit a mixture of properties and do not fit within these traditional phases of matter. To gain insight into the origins and manifestations of such mixed phase behavior, Valles' group is performing experiments at ultra-low temperatures on systems perched on the brink of a transition between a superconducting and a non-superconducting phase where mixed behavior should occur. In one case, they are using nano-technology to drive superconductors to become insulators by making them in the form of films thinner than a nano-meter (billionth of a meter) and perforated with nano-meter scale holes. In a second case, they are creating double layered films of a superconductor and a metal that produces a direct competition between these the metal and superconductor phases. These studies are serving as the PhD research training for two graduate students at Brown University. The students will develop expertise in nanotechnology, high sensitivity electrical measurements and low temperature techniques that will make them attractive to industry. In addition, undergraduate physics majors will engage in this research as part of senior thesis projects. TechnicalValles' group is investigating ultrathin superconducting films driven to the brink of a transition to a non-superconducting phase by the reduction of their superconducting order parameter amplitude. The work focuses on two distinguishing microscopic features of the superconductor: magnetic vortices and superconducting quasiparticles. The coexistence and competition between the superconducting and non-superconducting phases depend upon the vortex motion and the quasiparticle distribution. The results potentially will lend insight into similar phase competitions occurring in high temperature superconductors and other technologically promising materials. One set of these ultralow temperature investigations employs ultrathin homogeneous superconducting films patterned with hexagonal arrays of nanoscale size and spaced holes. The holes, which can pin vortices, will be used to detect the influence of vortex motion on the two dimensional superconductor to insulator transition. The second effort uses electron tunneling to characterize anomalies in the density of quasiparticle states that appear in ultrathin superconductor-normal metal bilayers. These states may drive a proposed superconductor to metal quantum phase transition in these composite films. The investigations serve as the PhD research training for two graduate students at Brown. These students will develop expertise in nanotechnology, high sensitivity electrical measurements and low temperature techniques that will make them attractive to industry. In addition, undergraduate physics majors will engage in related senior thesis projects.

非技术物理学家可以解释为什么有些材料像磁铁，有些像超导体，有些像绝缘体，根本不带电。然而，许多技术上有前途的新材料表现出混合的性质，并不适合这些传统的物质相。为了深入了解这种混合相行为的起源和表现，Valles的小组正在超低温下对处于超导和非超导相之间过渡边缘的系统进行实验，在这种过渡边缘应该发生混合行为。 在一个案例中，他们正在使用纳米技术来驱动超导体成为绝缘体，方法是将它们制成薄于纳米（十亿分之一米）的薄膜，并在薄膜上打孔。 在第二种情况下，他们正在创造超导体和金属的双层薄膜，在这些金属和超导体相之间产生直接竞争。 这些研究正在为布朗大学的两名研究生提供博士研究培训。学生将发展在纳米技术，高灵敏度电气测量和低温技术，这将使他们有吸引力的行业的专业知识。 此外，本科物理专业将从事这项研究作为高级论文项目的一部分。 TechnicalValles的小组正在研究通过减少超导序参量振幅而将超导薄膜驱动到非超导相转变的边缘。 这项工作集中在超导体的两个显著的微观特征：磁涡旋和超导准粒子。 超导相和非超导相的共存和竞争取决于涡旋运动和准粒子分布。 这些结果可能会让人们深入了解高温超导体和其他技术上有前途的材料中发生的类似相位竞争。 这些超低温研究中的一组采用了具有纳米尺寸和间隔孔的六边形阵列图案的非均匀超导膜。 这些能钉扎涡旋的孔洞将被用来探测涡旋运动对二维超导体到绝缘体转变的影响。 第二个努力使用电子隧穿的准粒子状态的密度，出现在超导正常的金属双层的特点异常。 这些状态可以驱动这些复合膜中的拟议超导体到金属的量子相变。 这些调查作为布朗大学两名研究生的博士研究培训。这些学生将开发纳米技术，高灵敏度电气测量和低温技术，这将使他们对行业的吸引力的专业知识。 此外，本科物理专业将从事相关的毕业论文项目。