Optical Spectroscopy of Electronic Matter Close to Quantum Criticality

接近量子临界点的电子物质的光谱学

• 批准号: 0454540
• 负责人: George Gruner
• 金额: $ 36万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-06-01 至 2008-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0454540&HistoricalAwards=false
• 关键词: Optical; Spectroscopy; Electronic; Matter; Close

***NON-TECHNICAL***In the vast majority of metals and semiconductors, such as copper and silicon, the behavior of electrons is well understood and is described by theories developed decades ago. The same is true for electronic devices, such as the transistor, built using such materials. The focus of this individual investigator research will be on materials where a change of composition or magnetic field leads to so-called "quantum phase transitions" between metallic, semiconducting and superconducting behavior. In the vicinity of such transitions, and also in molecular wires where the current flows in one dimension, new electron states arise. In order to gain insight into these new electron states the frequency dependent electrical conductivity will be measured in the microwave and millimeter wave range of the optical spectrum. Electronic devices having potentially new principles of operation and characteristics will also be fabricated using the same materials. The research will involve graduate and undergraduate students, who will be trained in both electronics and optics techniques. ***TECHNICAL***This individual investigator research will focus on the behavior of electrons under circumstances where the change of composition or magnetic field leads to a quantum phase transition. The low energy electrodynamics of the disorder driven metal-insulator transition and the magnetic field driven superconductor-insulator transition will be investigated through the measurement of the low energy optical response in the dc to the millimeter wave spectral range. The frequency dependent optical conductivity will be evaluated and analyzed in terms of scaling relations. The unusual metallic state in molecular nanowires will be also investigated using the same experimental tools. Electronic devices will be fabricated using the same materials. A search for evidence of novel collective electron states will be undertaken through the examination of the device characteristics. Both graduate and undergraduate students will be involved in research and technique development in the spectral range of electromagnetic spectrum that has significant application potential.

***非技术***在绝大多数金属和半导体中，例如铜和硅，电子的行为是充分理解的，并由几十年前开发的理论描述。使用此类材料构建的电子设备（例如晶体管）也是如此。该单个研究者研究的重点将放在材料上，其中组合物或磁场的变化导致金属，半导体和超导行为之间所谓的“量子相变”。在此类过渡的附近，以及在一个尺寸流动的分子线中，新电子状态出现。为了深入了解这些新电子状态，将在光谱的微波和毫米波范围内测量频率依赖性电导率。具有可能具有新的操作和特性原理的电子设备也将使用相同的材​​料制造。这项研究将涉及研究生和本科生，他们将接受电子和光学技术的培训。 ***技术***本个别研究者的研究将集中在组成或磁场导致量子相变的情况下的电子行为上。该疾病驱动的金属绝缘体转变和磁场驱动的超导体 - 绝缘体转变的低能电动力学将通过测量DC中的低能光学响应对毫米波光谱范围进行研究。将根据缩放关系评估和分析频率依赖的光学电导率。分子纳米线中的异常金属状态还将使用相同的实验工具研究。电子设备将使用相同的材​​料制造。搜索新型集体电子状态的证据将通过检查设备特征来进行。研究生和本科生都将参与具有巨大应用潜力的电磁光谱范围的研究和技术开发。