Quantum Phase Transitions in Nanostructured Superconductors in 2D

二维纳米结构超导体中的量子相变

• 批准号: 0203608
• 负责人: James Valles
• 金额: $ 27万
• 依托单位: Brown University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-07-01 至 2005-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0203608&HistoricalAwards=false
• 关键词: Quantum; Phase; Transitions; Nanostructured; Superconductors

This individual investigator award will support an experimental project that focuses on quasi-two-dimensional (2D), nanostructured films near their superconductor to nonsuperconductor quantum phase transitions (QPTs). Nanostructured proximity effect arrays, consisting of nanoscale superconducting grains embedded in a metal film and nanoscale wire arrays of superconducting films will be tuned through their superconductor to non-superconductor transitions and probed with electron magnetotransport and tunneling measurements at dilution refrigerator temperatures. The physics behind the QPTs in the nano-arrays, while similar to the well-known superconductor to insulator transitions is expected to sharply contrast with them. Because of the nanoscale dimensions, the phase and amplitude degrees of freedom in the superconducting order parameter, rather than just the phase, will vary strongly through these transitions. These experiments have the potential to reveal new classes of QPTs, and to provide physical insight into the origin of pseudogaps, and unconventional metallic phases in 2D correlated electron systems, such as the underdoped high temperature superconductors. While being immersed in important current problems in condensed matter physics, the students involved in this research will develop expertise in nanotechnology, scanning probe microscopies and low temperature techniques that will make them potentially attractive to industry and prepare them to be future leaders in science.The ability to produce and obtain images of electronic materials with features as small as a few billionths of a meter (a few nanometers) leads to new opportunities in technology and fundamental science. In technology, as more speed and power is demanded from our computers the dimensions of the electronics necessarily rapidly shrink toward the nanodimensions. On a fundamental side, new properties can emerge in seemingly familiar materials such as the metal copper when its dimensions are reduced to the nanometer scale. How small can a piece of copper be and still maintain the properties which are commonly associated with a metal? This individual investigator award supports a project that focuses on how the properties of superconducting materials (i.e. materials which lose all of their electrical resistance when cooled close to the absolute zero of temperature) change when some of their dimensions are pared down to the few nanometer scale. Measurements on two types of structures, nanostructured proximity effect arrays and nanoscale superconducting wire arrays, will test recent theories that suggest that the superconductors go through a dramatic change, becoming more like a metallic state of matter, when their dimensions become small enough. This metal state is predicted to have exotic properties that are similar to those of the technologically relevant high temperature superconductor materials. Thus, these nanostructured superconductors will serve as a model system that can lend new insight into other more complex materials. In addition, they will be used to address the simple and fundamental question of how finely structured can a superconductor be and still maintain its superconducting properties? While being immersed in important current problems in condensed matter physics, the students involved in this research will develop expertise in nanotechnology, scanning probe microscopies and low temperature techniques that will make them potentially attractive to industry and prepare them to be future leaders in science.

这项个人研究奖将支持一个实验项目，该项目专注于准二维（2D），纳米结构薄膜附近的超导体到非超导体量子相变（QPT）。 纳米结构的邻近效应阵列，包括嵌入在金属膜和纳米级线阵列的超导薄膜的纳米级超导晶粒将通过其超导体到非超导体的转变进行调整，并探测与电子磁输运和隧道测量稀释冰箱温度。 纳米阵列中QPT背后的物理原理虽然类似于众所周知的超导体到绝缘体的转变，但预计将与它们形成鲜明对比。 由于纳米尺度的尺寸，超导序参量的相位和振幅自由度，而不仅仅是相位，将通过这些转变强烈变化。 这些实验有可能揭示新的类QPT，并提供物理洞察的起源赝间隙，和非常规的金属相在二维相关电子系统，如欠掺杂的高温超导体。 在沉浸在凝聚态物理学的重要问题中的同时，参与这项研究的学生将发展纳米技术的专业知识，扫描探针显微镜和低温技术，这将使它们对工业具有潜在的吸引力，并使它们成为未来科学的领导者。（几纳米）为技术和基础科学带来了新的机遇。 在技术方面，随着计算机的速度和功率越来越高，电子产品的尺寸必然会迅速缩小到纳米尺寸。 从根本上说，当金属铜的尺寸减小到纳米尺度时，看似熟悉的材料会出现新的特性。 一块铜能有多小，仍然保持通常与金属相关的属性？ 这项个人研究奖支持一个项目，该项目的重点是超导材料（即当冷却到接近绝对零度时失去所有电阻的材料）的性质如何变化，当它们的一些尺寸缩小到几纳米尺度时。 对两种类型的结构，纳米结构邻近效应阵列和纳米级超导线阵列的测量，将测试最近的理论，这些理论表明，当超导体的尺寸变得足够小时，它们会发生巨大的变化，变得更像一种金属状态。 这种金属状态被预测具有与技术相关的高温超导材料相似的奇异特性。因此，这些纳米结构的超导体将作为一个模型系统，可以为其他更复杂的材料提供新的见解。 此外，它们将被用来解决一个简单而基本的问题，即超导体的结构可以有多精细，并且仍然保持其超导特性？ 在沉浸在凝聚态物理学的重要问题的同时，参与这项研究的学生将发展纳米技术，扫描探针显微镜和低温技术方面的专业知识，这将使他们对工业具有潜在的吸引力，并使他们成为未来的科学领导者。