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*在铜和硅等绝大多数金属和半导体中，电子的行为被很好地理解，并由几十年前开发的理论来描述。同样的道理也适用于使用这种材料制造的电子设备，如晶体管。这项个人研究的重点将放在材料上，即成分或磁场的变化会导致金属、半导体和超导行为之间的所谓“量子相变”。在这种跃迁附近，以及在电流沿一维流动的分子导线中，新的电子态出现。为了深入了解这些新的电子态，我们将在微波和毫米波光谱范围内测量随频率变化的电导率。具有潜在新的工作原理和特性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方面的培训。*技术*这项单独的研究人员将专注于电子在成分或磁场变化导致量子相变的情况下的行为。通过测量直流对毫米波的低能光学响应，研究无序驱动的金属-绝缘体相变和磁场驱动的超导体-绝缘体相变的低能电动力学。我们将根据标度关系来评估和分析随频率变化的光学传导性。分子纳米线中的异常金属状态也将使用相同的实验工具进行研究。电子设备将使用相同的材料制造。将通过对器件特性的检查来寻找新的集体电子态的证据。研究生和本科生都将参与电磁频谱领域的研究和技术开发，该领域具有重要的应用潜力。