CAREER: Broadband Microwave and THz Investigations of Correlated Electron and Nanostructure Systems

职业：相关电子和纳米结构系统的宽带微波和太赫兹研究

• 批准号: 0847652
• 负责人: Norman Armitage
• 金额: $ 52.5万
• 依托单位: Johns Hopkins 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: 2009-03-01 至 2014-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0847652&HistoricalAwards=false
• 关键词: CAREER; Broadband; Microwave; THz; Investigations

TECHNICAL ABSTRACTThe response of condensed matter to electromagnetic radiation is a fundamental probe of its electronic structure. Correlated systems and their nanostructures like quantum magnets, high-Tc superconductors, 2D electron gasses, graphene and others exhibit a multitude of novel properties as a result of strong electron-electron interactions, reduced dimensionality, and interfacial effects. Unfortunately, many of their natural time scales lie in the GHz and THz region of the electromagnetic spectrum that has been difficult to access in a broadband manner. The upper part of this range has even become known as the `Terahertz Gap', which is a range of frequencies (roughly 0.05 to 10 THz) and energy scales above what is easily accessible with radio-frequency and microwave electronics, but below that accessible easily with conventional optics. Recently, however, there have been a series of dramatic breakthroughs in broadband microwave GHz range and time-domain THz spectroscopy that allow measurements which were simply not possible previously. This proposal for research at The Johns Hopkins University is aimed at the exploitation of these recent dramatic advances in GHz and THz range spectroscopic techniques for the investigation of exotic electronic states of matter at low temperatures. The systems to be investigated include novel dielectrics, electronic glasses, nanostructures such as interfacial metal heterostructures and graphene, and materials in proximity to quantum (T=0) phase transitions. These systems are of central importance for intellectual issues at the forefront of condensed matter physics and their exploration in the GHz and THz spectral range offers great scientific opportunity. The proposed work is of particular educational value to students owing to the material science and low frequency electrodynamics techniques that will be employed and which are finding broad application in research and private industry. In this regards, specific teaching laboratories will be developed. Public outreach activities in the form of the Johns Hopkins Physics Fair will also be realized.NON-TECHNICAL ABSTRACT: It is hardly an exaggeration that most of what we know about physical systems comes from their response to perturbations at their characteristic frequencies. For instance, the fundamental tone of a plucked violin string depends on the length of the string, the tension in it, and its thickness. This is true from the acoustics of a violin to the energies of atoms. Unfortunately the natural frequency scales of many solid materials fall in a range which has been prohibitively difficult to access technically until recently. This project takes advantage of recent dramatic technical advances in THz and microwave spectroscopy to characterize the natural frequency scales of solids. Material systems like superconductors, which can conduct electricity without resistance and various magnetic states will be studied. The investigations performed herein will give absolutely essential information to develop new materials with important technological implications. These technological developments are coupled to a broad initiative in education and outreach. The proposed work is of particular educational value to students owing to the material science and low frequency electrodynamics techniques that will be employed and which are finding broad application in research and private industry. Specific teaching laboratories will be developed. Public outreach activities in the form of the Johns Hopkins Physics Fair will also be realized.

凝聚态物质对电磁辐射的响应是研究其电子结构的基础。相关体系及其纳米结构，如量子磁体、高T_c超导体、2D电子气、石墨烯等，由于强烈的电子-电子相互作用、降维和界面效应而显示出许多新的性质。不幸的是，它们的许多自然时间尺度位于电磁频谱的GHz和THz区域，这已经很难以宽带方式访问。这个范围的上半部分甚至被称为“太赫兹差距”，这是一个频率范围(大约0.05至10太赫兹)和能量范围，高于射频和微波电子学容易获得的范围，但低于传统光学容易获得的频率和能量范围。然而，最近，在宽带微波GHz范围和时间域太赫兹光谱学方面取得了一系列戏剧性的突破，使得以前根本不可能进行的测量成为可能。约翰霍普金斯大学的这项研究建议旨在利用最近在GHz和THz范围光谱技术方面的巨大进步来研究低温下物质的奇异电子态。要研究的体系包括新型介电材料、电子玻璃、界面金属异质结构和石墨烯等纳米结构，以及接近量子(T=0)相变的材料。这些系统对于凝聚态物理前沿的智力问题具有核心重要性，它们在GHz和THz光谱范围内的探索提供了巨大的科学机会。由于材料科学和低频电动力学技术将在研究和私营工业中得到广泛应用，因此拟议的工作对学生具有特别的教育价值。在这方面，将发展专门的教学实验室。约翰霍普金斯大学物理博览会形式的公众推广活动也将实现。非技术摘要：毫不夸张地说，我们对物理系统的大部分了解来自于它们对特征频率扰动的反应。例如，一根拨动的小提琴弦的基音取决于弦的长度、弦中的张力和弦的厚度。从小提琴的声学到原子的能量，都是如此。不幸的是，许多固体材料的自然频率范围一直在技术上难以达到的范围内，直到最近。该项目利用最近在太赫兹和微波光谱学方面的巨大技术进步来表征固体的自然频率尺度。像超导体这样的材料系统，可以在没有电阻和各种磁态的情况下导电，将被研究。这里进行的研究将为开发具有重要技术意义的新材料提供绝对必要的信息。这些技术发展与教育和外联方面的广泛倡议相辅相成。由于材料科学和低频电动力学技术将在研究和私营工业中得到广泛应用，因此拟议的工作对学生具有特别的教育价值。发展具体的教学实验室。还将开展约翰·霍普金斯物理博览会形式的公众宣传活动。