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.

***非技术性*** 在绝大多数金属和半导体（例如铜和硅）中，电子的行为已得到很好的理解，并且由几十年前开发的理论进行了描述。对于使用此类材料制造的电子设备（例如晶体管）也是如此。这项个人研究人员的研究重点将放在成分或磁场变化导致金属、半导体和超导行为之间所谓“量子相变”的材料上。在这种跃迁附近，以及电流在一维流动的分子线中，会出现新的电子态。为了深入了解这些新的电子态，将在光谱的微波和毫米波范围内测量频率相关的电导率。具有潜在新操作原理和特性的电子设备也将使用相同的材​​料制造。该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*** 这项个人研究人员的研究将重点关注成分或磁场变化导致量子相变的情况下电子的行为。将通过测量直流至毫米波光谱范围内的低能光学响应来研究无序驱动的金属-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。频率相关的光导率将根据比例关系进行评估和分析。分子纳米线中不寻常的金属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。将通过检查器件特性来寻找新型集体电子态的证据。研究生和本科生都将参与具有巨大应用潜力的电磁波谱范围内的研究和技术开发。