Probing and manipulating strained interfaces with oxide superconductors

非技术描述：超导体能够无损耗地携带电流，这是自然界最奇异的物理现象之一。这种能力可以用临界电流密度Jc，超导电性来定量描述。增强的JC将为恢复电网的可靠性和提高电网的容量和效率提供强大的新机遇，这被视为一项重大的工程挑战。随着能源需求的增加和现有电网的老化，美国将面临危机，无法提供充足、可靠的清洁能源电力，以满足国家未来的生产力、经济增长和生活质量。氧化物高温超导体(HTS)的发现使其在液氮温度下的应用成为可能，但由于其特殊的物理性质也提出了一个引人入胜的研究课题，从而对JC产生了深远的影响。在过去的二十年里，在高温超导中提高JC一直是世界各国在应用超导领域努力的焦点。特别是，一个长期存在的问题是，通过对材料微结构的精确控制，能否在实际高温超导导体中达到理论预测的最大JC(即所谓的去配对极限)。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，通过控制纳米级的电流来设计物理特性的方法代表了与传统的经验方法的飞跃，在传统的经验方法中，高温超导材料的开发没有精确的基础物理指导。这项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。技术描述：以纳米级精度控制微观结构是获得具有非凡功能的材料的关键，由于缺乏对基本物理的了解和在这种规模上设计原子排列的方法，这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。一种集成的建模-合成-表征方法被用来解决这样一个挑战，即理解、预测和操纵嵌入在YBa2Cu3O7-d(YBCO)高温超导薄膜中的人工钉扎中心(APC)功能纳米复合材料中的应变界面。其目标是实现APC的可控自组装，具有精确设计的形态、取向、密度和受控的APC/HTS接口，以基于基本的物理设计规则最佳地发挥作用。提出了四个完整的主题；所有主题都集中在理解和操纵界面应变以实现高JC的APC/YBCO纳米复合材料的可控生长。主题1通过了解不同掺杂浓度和YBCO基质应变下的微观控制机制，重点研究了APC线性排列的这种构型的相图。应变对相关界面的作用将被量化。主题2研究了YBCO基质中线性APC的应变界面对APC/HTS纳米复合材料JC的影响，并探索了减少或消除这种应变界面上的氧无序对纳米复合材料超导电性的不利影响的方法。主题3集中在寻找直径更小、接近超导相干长度的线性APC，以及在非常高的磁场下获得更高JC的更高密度、相关的线性APC。主题4研究纳米结构自发自组装的动力学。

NON-TECHNICAL DESCRIPTION: Superconductors are capable of carrying electric current without loss, one of the most exotic physical phenomena in nature. This capability is described quantitatively by critical current density Jc, superconductivity. Enhanced Jc will provide powerful new opportunities for restoring the reliability of the power grid and increasing both its capacity and efficiency, regarded as an engineering grand challenge. As energy demands increase and our existing grid ages, the USA will face a crisis situation to provide abundant, reliable clean energy power to meet the nation's future productivity, economic growth and quality of life. The discovery of oxide high temperature superconductors (HTSs) made superconductor applications possible at liquid nitrogen temperature, but also presented a fascinating research topic due to their unusual physical properties, resulting in profound effects on Jc. Raising Jc in HTSs 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 theoretically predicted maximum Jc (so-called depairing limit) can be reached in practical HTS conductors through precise control of material microstructures with nanoscale precision. 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 electric current 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 a research also provides the forefront of education for the next generation in the fields of nanoscience and material science.TECHNICAL DESCRIPTION: Controlling microstructure with nanoscale precision is the key to achieving materials with extraordinary functionality and has been a major challenge in material research of HTS and other technologically interesting materials due to lack of understanding of fundamental physics and approaches for engineering atomic arrangement at such a scale. An integrated modeling-synthesis-characterization approach is being used to address such a challenge to understand, predict and manipulate the strained interfaces in functional nanocomposites of artificial pinning centers (APCs) embedded in HTS films of YBa2Cu3O7-d (YBCO). The goal is to achieve controllable self-assembly of APCs with precisely designed morphology, orientation, density and controlled APC/HTS interfaces to function optimally based on the basic physics design rules. Four integrated themes are proposed; all are focused on understanding and manipulating interface strains towards controllable growth of APC/YBCO nanocomposites for high Jc. Theme 1 focuses on the study of this configuration's phase diagram with a linear arrangement of APCs through understanding the microscopic controlling mechanisms at different dopant concentrations and YBCO matrix strains. The role of strain on the relevant interfaces will be quantified. Theme 2 investigates the effect of strained interfaces of linear APCs in a YBCO matrix on the Jc of the APC/HTS nanocomposites and explores ways to reduce or eliminate the detrimental effect of the oxygen disorder at such a strained interface on superconductivity of the nanocomposites films. Theme 3 focuses on a search for linear APCs with smaller diameters that approach the superconducting coherence length as well as higher density, correlated linear APCs for higher Jc at very high magnetic fields. Theme 4 investigates the kinetics of the spontaneous self-assembly of nanostructures.