Optical Spectroscopy of Electronic Matter Close to Quantum Criticality

在绝大多数金属和半导体中，如铜和硅，电子的行为已经被很好地理解，并由几十年前发展起来的理论来描述。使用这种材料制造的电子设备，如晶体管，也是如此。这名个人研究者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的“量子相变”的材料上。在这样的跃迁附近，以及在电流一维流动的分子线中，新的电子态出现了。为了深入了解这些新的电子状态，将在光谱的微波和毫米波范围内测量频率相关的电导率。具有潜在的新操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。这项个人研究将集中在电子在成分或磁场变化导致量子相变的情况下的行为。通过测量直流到毫米波光谱范围内的低能光响应，研究无序驱动的金属-绝缘体跃迁和磁场驱动的超导体-绝缘体跃迁的低能电动力学。频率相关的光电导率将根据标度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。电子设备将使用同样的材料制造。寻找新的集体电子态的证据将通过对器件特性的检查来进行。研究生和本科生将参与具有重要应用潜力的电磁波谱频谱范围的研究和技术开发。

***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.