Coherent Spectroscopy of Vortex-State Electrodynamics

9510353 Orenstein高Tc铜酸盐超导体的光学响应自发现以来一直是激烈研究的主题。看来，从微波到红外线的反应的一致画面终于出现了。然而，已经实现的理解在很大程度上限于零磁场。拟议的研究旨在发展一个彻底的理解，在响应磁场产生的涡旋状态的光学响应。 研究的重点是太赫兹的频率范围，这是至关重要的一个在铜氧化物中的涡旋动力学，因为它对应于准粒子激发的涡核中的差距。 关键的实验工具是太赫兹时域光谱，这是测量微波和红外域之间的光谱范围内的介质的宽带响应的最成功的方法。在该技术中，通过分解直接测量复响应函数， 的 透射系数 的 近单周期皮秒电场脉冲。这些脉冲是通过使用飞秒锁模激光器产生和光电检测的。 %%% 超导体的惊人特性是直流电阻的消失。 然而，在零频率以上，超导体会产生可测量的电阻，其性质是不同材料中超导性的区别特征。从微波到可见光，高温铜氧化物超导体在零外加磁场下的电阻率一直是人们研究的热点。 这 该项目研究了磁场下的基本和技术上重要的制度。 该提案旨在发展 一 全面了解 铜氧化物超导体在“涡旋状态”，这出现在大磁场的存在。研究重点是太赫兹光谱区域，这是铜氧化物的关键范围，并使用一种强大的新光谱工具，太赫兹时域光谱。广泛 范围 的 将合成更高质量的薄膜 和调查。结果将测试和刺激理论工作，这是发展迅速的证据出现在高温超导体的非常规起源。 ***

9510353 Orenstein The optical response of high-Tc cuprate superconductors has been the subject of intense investigations since their discovery. It appears that a consistent picture of the responses, from microwave to infrared is finally emerging. However, the understanding that has been achieved is largely confined to zero magnetic field. The proposed research seeks to develop a thorough understanding of the optical response in the vortex-state which arises in response to magnetic field. The study focuses on the terahertz frequency range, which is the crucial one for vortex dynamics in the cuprates because it corresponds to the gap for quasi particle excitations in the vortex core. The key experimental tool is terahertz time-domain spectroscopy, which is the most successful approach to measuring broad band response of the media in the spectral range between the microwave and infra-red domains. In this technique the complex response function is measured directly by resolving the transmission coefficient of nearly-single-cycle picosecond electric field pulses. These pulses are generated and detected optoelectronically through the use of a femtosecond mode- locked laser. %%% The spectacular property of superconductors is the vanishing of the dc resistance. However, above zero frequency, superconductors develop measurable resistance, whose properties are a distinguishing feature of superconductivity in different materials. The resistivity of high temperature cuprate superconductors in zero applied magnetic field, from microwave to visible frequencies, has been studied intensively. This project investigates the fundamentally and technologically important regime of under magnetic field. The proposal seeks to develop a thorough understanding of the response of cuprate superconductors in the "vortex state" which arises in the presence of large magnetic field. The research focus es on the terahertz region of the spectrum, which is the crucial range for the cuprates, and uses a powerful new spectroscopic tool, terahertz time-domain spectroscopy. A broad range of high quality films will be synthesized and investigated . The results will test and stimulate theoretical work, which is evolving rapidly as evidence emerges for unconventional origins of superconductivity in HTS. ***