Probing and manipulating superconductivity in nanostructures

探测和操纵纳米结构中的超导性

• 批准号: 1105986
• 负责人: Judy Wu
• 金额: $ 50.46万
• 依托单位: University of Kansas Center for Research Inc
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-06-15 至 2016-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1105986&HistoricalAwards=false
• 关键词: Probing; manipulating; superconductivity; nanostructures

NON-TECHNICAL DESCRIPTION: Superconductivity can play a significant role in deregulated electricity markets and in lessening carbon dioxide emission and other environmental impacts. The layered structure of high temperature superconductor (HTS) materials result in many dramatic effects in their physical properties especially their current carrying capability, or critical current density, Jc, which is a critical parameter for numerous applications in electrical devices and systems. Raising Jc has been the focus of world-wide efforts in the field of applied superconductivity during the past two decades. In particular, a long-standing question is whether the theoretical depairing limit (Jd) can be reached in practical HTS conductors through self-assembly of nanostructures designed to pin the magnetic vortices. Recent advances in nanoscience have provided fresh opportunities in engineering the microstructures of HTS materials. The approach undertaken in this project of designing physical properties via controlling the charge carriers at the nanoscale represents a leap forward from the traditionally empirical method in which the HTS materials have been developed without a precise guidance of fundamental physics. Such research also provides the forefront of education for the next generation in the fields of nanoscience and material science.TECHNICAL DETAILS: Controlling microstructure with nanoscale precision has been a major challenge in material research of HTS and other technologically interesting materials due to the difficulties in processing controllably at nanoscale, and the lack of understanding of the physics at such a scale. To address this challenge, several novel processes for strain engineering at the nanoscale have been developed in PI?s group through prior NSF support. In particular, theoretical modeling and numerical simulation have been coherently integrated into this research to provide insights and guidance in nanostructure manipulation and fabrication. The complement of theory and experiment continues in this project provides an efficient approach in understanding the growth mechanism of nanostructures of HTS. Such an understanding is ubiquitous to ultimately achieve the capability to manipulate the nanostructure properties. This research divides into three themes. Theme 1 focuses on investigation of the microscopic growth mechanisms (nucleation, initiation, evolution, etc.) of nanostructures such as aligned arrays of nanotubes and nanorods in HTS YBa2Cu3O7 (YBCO) films. Theme 2 continues focuses on developing theoretical models and numerical simulations to provide insight into the microscopic growth mechanism of nanostructures in YBCO. Extending the modeling and simulation to cover a large range of HTS materials and doping impurities helps explain experimental observations and assists in fabricating nanostructures with specific physical properties. Theme 3 explores superconductivity in graphene. The microscopic transport behavior of massless 2D Dirac fermions in the superconducting state will be studied for a superconductor-graphene-superconductor structure, e.g., Nb-graphene-Nb Josephson junctions. Experimental investigation of the superconductivity in graphene is still in its infancy despite of many exciting theoretical studies. This Nb-graphene-Nb hybrid system may provide a unique system for exploring the physics of the relativistic Josephson effect.

非技术描述：超导性可以在放松管制的电力市场以及减少二氧化碳排放和其他环境影响方面发挥重要作用。高温超导(HTS)材料的层状结构对其物理性能产生了很大的影响，特别是其载流能力，即临界电流密度Jc，这是许多电子设备和系统中应用的关键参数。在过去的二十年里，提高JC一直是世界范围内应用超导领域努力的焦点。特别是，一个长期存在的问题是，在实际的高温超导导体中，是否可以通过设计用于钉扎磁涡的纳米结构的自组装来达到理论去配对极限(JD)。纳米科学的最新进展为设计高温超导材料的微结构提供了新的机会。在这个项目中，通过在纳米尺度上控制载流子来设计物理性质的方法，代表着对传统经验方法的飞跃，在这种方法中，高温超导材料是在没有精确的基础物理指导的情况下开发的。这些研究还为下一代在纳米科学和材料科学领域提供了教育的前沿。技术细节：由于在纳米级进行可控加工的困难，以及对这种规模的物理缺乏了解，以纳米级精度控制微观结构一直是高温超导和其他技术感兴趣的材料材料研究的主要挑战。为了应对这一挑战，在先前的美国国家科学基金会的支持下，皮？S团队已经开发出了几种纳米尺度的应变工程新工艺。特别是，理论建模和数值模拟被连贯地整合到这项研究中，以提供对纳米结构操纵和制造的洞察和指导。理论和实验的补充为理解高温超导纳米结构的生长机制提供了一条有效的途径。这样的理解对于最终实现操纵纳米结构属性的能力是普遍存在的。本研究分为三个主题。主题1着重于微观生长机制(成核、引发、演化等)的研究。高温超导YBa2Cu3O7(YBCO)薄膜中的纳米结构，如纳米管和纳米棒的排列阵列。主题2继续侧重于开发理论模型和数值模拟，以深入了解YBCO中纳米结构的微观生长机制。将建模和模拟扩展到涵盖广泛的高温超导材料和掺杂杂质，有助于解释实验观察结果，并有助于制造具有特定物理性质的纳米结构。主题3探索石墨烯的超导电性。对于超导体-石墨烯-超导体结构，例如Nb-石墨烯-Nb约瑟夫森结，我们将研究超导状态下无质量2D Dirac费米子的微观输运行为。尽管有许多激动人心的理论研究，但对石墨烯超导电性的实验研究仍处于起步阶段。这种Nb-石墨烯-Nb杂化系统可能为探索相对论约瑟夫森效应的物理提供了一个独特的系统。