Infrared Studies of Cuprate Superconductors

这个个人研究者奖是由能源部的基础能源科学计划共同资助。 它支持一个项目，该项目将通过测量从远红外光谱范围内的光学电导率来研究广泛的铜酸盐材料，其中超流体密度主导响应，通过中频，来自配对冷凝物的大部分光谱重量，到观察到非费米液体行为和电荷转移激发的光学范围。该项目的一个重点将是抑制超流体密度的影响，首先试图了解即使在最佳掺杂下，这个数量也非常低。第二个重点将是过掺杂材料，努力寻找和表征超导状态内的相变，并了解高掺杂超导体到金属的转变。 第三，该项目将研究相图的电子掺杂侧，最近接近最佳掺杂的实验已经发现了d波超导性的证据。最后的重点是研究大磁场对这些材料的影响。 这将包括在低温下在高磁场中观察到的超导体到绝缘体的转变的调查。从事这项研究的学生将涉及新材料、复杂的光学测量、新材料理论、低温技术、真空沉积、传输研究和光学数据分析方法。这项个人研究者奖由能源部基础能源科学计划共同资助。 它支持一个利用红外线和可见光研究高转变温度超导体的项目，以测量与超导性相关的影响。一个独特的方面是使用的波长范围很广;它们几乎跨越10，000倍。这种广泛的覆盖范围允许研究超导电子的集体效应，称为“凝聚”，以及晶体中原子的振动和电子的散射。这些实验解决了一些当前感兴趣的问题，旨在增加我们对潜在技术上有用的高温超导体的理解。从事这项研究的学生将参与新材料，复杂的光学测量，新材料理论，低温技术，真空沉积，运输研究和光学数据分析方法。

This individual investigator award is co-funded by the Department of Energy's Basic Energy Sciences program. It supports a project that will study a wide class of cuprate materials by measuring the optical conductivity over a spectral range from the far infrared, where the superfluid density dominates the response, through intermediate frequencies, from which comes most of the spectral weight of the paired condensate, to the optical range where non-Fermi liquid behavior and charge-transfer excitations are observed. One focus of the project will be effects that suppress the superfluid density, beginning with an attempt to understand the fact that even at optimal doping this quantity is anomalously low. A second focus will be the overdoped materials, in an effort to search for and characterize phase transitions within the superconducting state, and to understand the high-doping superconductor-to-metal transition. Third, the project will investigate the electron-doped side of the phase diagram, where recent experiments near optimal doping have found evidence of d-wave superconductivity. The final focus is to study the effect of a large magnetic field on these materials. This will include an investigation of the superconductor-to-insulator transition that has been observed in high magnetic fields at low temperatures. Students working on this research will be involved with novel materials, sophisticated optical measurements, theories of novel materials, low-temperature techniques, vacuum deposition, transport studies, and methods for analysis of optical data.This individual investigator award is co-funded by the Department of Energy's Basic Energy Sciences program. It supports a project to study of high-transition temperature superconductors using infrared and visible light to measure effects associated with the superconductivity. One unique aspect is the wide range of wavelengths employed; they span almost a factor of 10,000. This wide coverage allows studies of both collective effects of the superconducting electrons, called "the condensate," and also vibrations of the atoms in the crystal and absorptions by the electrons. The experiments address a number of questions of intense current interest aimed at increasing our understanding of the potentially technologically useful high temperature superconductors. Students working on this research become involved with novel materials, sophisticated optical measurements, theories of novel materials, low-temperature techniques, vacuum deposition, transport studies, and methods for analysis of optical data.