Quantum Coherence and Mesoscopic Physics

量子相干性和介观物理

• 批准号: 0405238
• 负责人: Norman Birge
• 金额: --
• 依托单位: Michigan State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-07-01 至 2008-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0405238&HistoricalAwards=false
• 关键词: Quantum; Coherence; Mesoscopic; Physics

This condensed matter physics project deals with "mesoscopic" metallic samples - i.e. samples with submicron dimensions. These material can display surprising behavior, particularly in hybrid samples containing different types of materials - normal metals, superconductors, and ferromagnets. Recent theoretical predictions challenge our understanding of these materials; contradicting the long-held view that ferromagnets can not sustain superconducting correlations over distances longer than a few nanometers. This experimental project will test that prediction and others concerning electrical transport across superconductor/ferromagnet and superconductor/normal metal interfaces. In addition, experiments will probe the transport properties of normal metals when both disorder and electron-electron interactions are very strong - a regime poorly understood theoretically. Experimental research in mesoscopic physics plays an important role in educating the next generation of scientists. Graduate students involved in this project acquire expertise in modern nanofabrication techniques used in the semiconductor industry, which are also crucial to the future development and applications of nanosciences. The students are trained for careers in industry, academia, and government.When metallic samples are fabricated with very small dimensions - in the range of a micrometer - they exhibit many electrical properties not observed in larger samples. Some of the novel properties are evident at room temperature, while others are revealed only at low temperature, when electrons preserve quantum-mechanical phase coherence over many micrometers. The study of small metallic samples, called "mesoscopic physics", is a rich discipline and has led to a deeper understanding of many aspects of solid-state physics. This project addresses several current problems in mesoscopic physics, including the role of electron-electron interactions in highly-disordered metals, the complex interplay between ferromagnetic and superconducting metals in contact with each other, and the unusual behavior of superconducting/normal metal Josephson junctions driven far from equilibrium. Experimental research in mesoscopic physics plays an important role in educating the next generation of scientists. Graduate students working on these projects acquire expertise in sample processing techniques used in the microelectronics industry. The physical principles and experimental techniques developed in this kind of work are crucial to the future development and applications of nanosciences. The students and post-doctoral researchers are well trained for careers in industry, academia, and government.

这个凝聚态物理项目涉及“介观”金属样品-即亚微米尺寸的样品。这些材料可以显示出令人惊讶的行为，特别是在包含不同类型材料的混合样品中-正常金属，超导体和铁磁体。 最近的理论预测挑战了我们对这些材料的理解;与长期以来的观点相矛盾，即铁磁体不能在超过几纳米的距离上维持超导相关性。这个实验项目将测试预测和其他关于超导体/铁磁体和超导体/正常金属界面的电输运。此外，实验将探测当无序和电子-电子相互作用都非常强时正常金属的输运性质-理论上对这种机制知之甚少。 介观物理的实验研究在培养下一代科学家方面起着重要作用。参与该项目的研究生将获得半导体工业中使用的现代纳米纤维技术的专业知识，这对纳米科学的未来发展和应用也至关重要。当金属样品被制造成非常小的尺寸时-在微米范围内-它们表现出许多在较大样品中观察不到的电学特性。一些新的性质在室温下是明显的，而另一些只有在低温下才能发现，当电子在许多微米内保持量子力学相位相干性时。对小金属样品的研究，称为“介观物理学”，是一门内容丰富的学科，并使人们对固态物理的许多方面有了更深入的了解。该项目解决了介观物理学中的几个当前问题，包括电子-电子相互作用在高度无序金属中的作用，相互接触的铁磁和超导金属之间的复杂相互作用，以及超导/正常金属约瑟夫森结远离平衡的不寻常行为。介观物理的实验研究在培养下一代科学家方面起着重要作用。从事这些项目的研究生获得了微电子行业中使用的样品处理技术的专业知识。在这类工作中发展的物理原理和实验技术对纳米科学的未来发展和应用至关重要。 学生和博士后研究人员在工业，学术界和政府的职业生涯训练有素。