International Research Fellowship Program: Infrared and Optical Studies of Quantum Phase Transitions

0402699阿米蒂奇国际研究奖学金计划使美国科学家和工程师能够在国外进行三到二十四个月的研究。 该计划的奖项提供了联合研究的机会，并利用国外独特或互补的设施，专业知识和实验条件。该奖项将支持诺曼·阿米蒂奇博士与德克·货车德马勒博士在瑞士日内瓦大学进行为期16个月的研究。该项目涉及研究凝聚态系统在所谓的量子相变（QPT）附近的光学和红外特性。 这是凝聚态物理学中一些最具挑战性和最有趣的问题的前沿话题。 曾经被认为是理论上的好奇心，现在越来越清楚的是，附近QPT的存在可能是理解凝聚态物理学前沿许多系统不寻常行为的关键。 相关电子系统的光学和红外响应，如超导体和新的磁状态，正在调查，因为它们是通过一个外部参数（如压力，载流子密度，或磁场）通过这样的过渡之间的各种磁性和超导基态接近绝对零度温度调谐。 这项工作是由日内瓦大学的Dirk货车der Marel教授的团队完成的，他们使用了货车der Marel博士实验室的最先进设施和目前安装在瑞士光源（SLS）同步加速器上的新红外系统。 货车der Marel教授目前的工作集中在强关联电子系统的低能激发光谱，使用各种红外和光学光谱探针。 位于日内瓦的实验室为该项目配备了独特的设备，是世界上进行此类调查的顶级实验室之一。 然而，光学研究的压力调谐QPT（如在重费米子系统中发现的），需要使用小束斑耦合到金刚石砧压力单元。 这是一个与传统的基于实验室的红外或光学源不兼容的要求，但由于红外同步辐射（IRSR）源的出现而成为可能。 该项目的独特之处之一是在SLS中使用新委托的红外光束线。

0402699ArmitageThe International Research Fellowship Program enables U.S. scientists and engineers to conduct three to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.This award will support a sixteen-month research fellowship by Dr. Norman P. Armitage to work with Dr. Dirk van der Marle at the University of Geneva in Switzerland. This project concerns the study of optical and infrared properties of condensed matter systems near so-called quantum phase transition (QPTs). This a topic at the forefront of some of the most challenging and interesting problems in condensed matter physics. Once thought to be a theoretical curiosity, it is becoming increasingly clear that the existence of nearby QPTs may hold the key to understanding the unusual behavior of many systems at the forefront of condensed matter physics. The optical and infrared response of correlated electron systems, such as superconductors and novel magnetic states, are being investigated as they are tuned via an external parameter (e.g. pressure, carrier density, or magnetic field) through such a transition between various magnetic and superconducting ground states near absolute zero temperature. The work is being done in the group of Prof. Dirk van der Marel at the University of Geneva using both the state-of-the-art facilities of Dr. van der Marel's lab and new infrared systems being currently installed at the Swiss Light Source (SLS) synchrotron. Prof. van der Marel's present work concentrates on the low energy excitation spectra of strongly correlated electron systems, using various infrared and optical spectroscopic probes. The lab in Geneva is uniquely equipped for this project as one of the top laboratories in the world for such investigations. However, the optical study of pressure-tuned QPTs (such as those found in heavy fermion systems), necessitates the use of small beam spots for coupling into a diamond anvil pressure cells. This is a requirement incompatible with traditional lab based infrared or optical sources, but made possible by the advent of infrared synchrotron radiation (IRSR) sources. One of the unique aspects of this project is the use of newly commissioned infrared beamlines at the SLS.