Probing Cooper Pair Insulator to Superconductor Transitions in Amorphous Films

探测非晶薄膜中库珀对绝缘体到超导体的转变

• 批准号: 0907357
• 负责人: James Valles
• 金额: $ 40万
• 依托单位: Brown University
• 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: 2009-11-01 至 2014-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0907357&HistoricalAwards=false
• 关键词: Probing; Cooper; Pair; Insulator; Superconductor

****NON-TECHNICAL ABSTRACT?****This project consists of experiments on materials patterned with nano-meter scale features that exhibit exotic electrical properties when cooled to near the absolute zero of temperature. The materials consist of films of the element Bi that have been perforated with a nano-meter scale honeycomb array of holes. Without the holes, these films become "superconducting" through a process in which the electrons form pairs, called Cooper pairs that are able to move through the Bi without friction. With the holes, these films can form into the opposite state: an electrical insulator. This insulator, surprisingly, also contains Cooper pairs. The goal of this project is to characterize this state with the objectives of determining the factors that prevent the Cooper pairs from superconducting. Experiments on films patterned with varying hole geometries will determine which geometrical characteristics produce the novel state. In addition, techniques to weaken the Cooper pairs will be employed to test the hypothesis that the Cooper pairing is essential to the formation of the insulator state. Results from this project will enhance our understanding of superconductivity and in particular, the behavior of some high temperature superconductors. In addition, these investigations provide intensive training for graduate and undergraduate students in high technology, research techniques and forefront physics issues and thus, help build the nation?s technological workforce. ****TECHNICAL ABSTRACT?****This project consists of experiments at dilution refrigerator temperatures on ultrathin films of superconducting materials, patterned with a nano-meter scale honeycomb array of holes. The goal is to characterize a recently discovered, novel insulating state of these films. This state contains Cooper pairs, the primary constituents of superconductors, but the Cooper pairs are localized. The objectives are to determine the factors responsible for the Cooper pair localization. The patterned films are created by depositing Bi onto anodized aluminum oxide templates that are perforated by deep holes. Investigations of films patterned with holes of varying radii and spacing will be performed to determine the geometrical factors influencing the Cooper pair localization. Also, investigations of how the insulating state responds to the introduction of magnetic impurities that can weaken and destroy Cooper pairing will be performed, thereby testing whether the Cooper pairing is essential to the formation of the insulating state These results are expected to impact investigations of other systems near the quantum superconductor to insulator transition and high temperature superconducting materials that exhibit states with finite resistance, such as the pseudo-gap state in under-doped cuprates, which might contain Cooper pairs. The project and its activities also serve as the PhD research training for two graduate students at Brown. It immerses them in frontier issues in condensed matter physics and helps them develop technical expertise that will make them attractive to industry or academia.

****非技术摘要？****该项目由对具有纳米计尺度特征的材料进行实验，这些材料在冷却至接近温度的绝对零时具有外来电气性能。 这些材料由元素BI的膜组成，这些元素BI已用纳米米尺度的蜂窝阵列穿孔。在没有孔的情况下，这些膜通过电子对形成库珀对的过程就会“超导”，这些过程称为库珀对，能够在无摩擦的情况下移动BI。 使用孔，这些膜可以形成相反的状态：电绝缘体。 令人惊讶的是，这种绝缘子还包含库珀对。 该项目的目的是通过确定阻止库珀对超导的因素来表征这种状态。 在具有不同孔几何形成的膜上进行的实验将确定哪些几何特征产生了新状态。 此外，将采用削弱库珀对的技术来检验库珀配对对于形成绝缘体状态至关重要的假设。 该项目的结果将增强我们对超导性的理解，尤其是某些高温超导体的行为。 此外，这些调查为高科技，研究技术和前列物理问题的研究生和本科生提供了深入的培训，因此有助于建立国家的技术劳动力。 ****技术摘要吗？ 目的是表征这些电影的最近发现的新型绝缘状态。该状态包含库珀对，这是超导体的主要成分，但库珀对被定位。 这些目标是确定负责库珀对本地化的因素。图案膜是通过将BI沉积到阳极氧化铝模板上而产生的，这些氧化铝模板被深孔穿孔。 将对用不同半径和间距的孔模式的膜进行调查，以确定影响库珀对定位的几何因素。 此外，还将进行对绝缘状态如何应对引入可以削弱和破坏库珀配对的磁杂质的调查，从而测试库珀配对是否对于形成绝缘状态的库珀配对是否必不可少铜层，可能包含库珀对。 该项目及其活动还为布朗的两名研究生提供博士研究培训。它使它们沉浸在凝结物理学的边界问题中，并帮助他们发展技术专长，使它们对行业或学术界有吸引力。