Dynamical Properties of Superconductors

超导体的动力学特性

基本信息

批准号：
9732800
负责人：
Christopher Lobb
金额：
$ 26.4万
依托单位：
University of Maryland, College Park
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
1998
资助国家：
美国
起止时间：
1998-08-01 至 2001-07-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=9732800&HistoricalAwards=false
关键词：
Dynamical Properties Superconductors

项目摘要

w:\awards\awards96\*.doc 9732800 Lobb This experimental research project deals with dynamical properties of superconductors, with emphasis on high Tc materials. The Hall effect will be studied in NCCO and PCCO superconductors of varying stoichiometries, in order to determine whether the anomalous sign change of the Hall effect arises from vortex pinning or from charge acquired by the vortices. The Hall effect and vortex correlations will also be studied using a Giaever flux transformer, which provides coupling between two vortex systems. A second dynamical regime that will be studied arises when fluctuations near the superconducting-normal transition in zero field lead to time-varying phases. The critical exponent parameters associated with this transition will be probed with a comprehensive set of measurements, from DC current-voltage characteristics, to mutual inductance measurements up to 100kHz, to microwave response measurements. These measurements will be done in thick (3-D) YBCO samples as well as in progressively thinner samples, so that the crossover to 2-D can be studied. This research program is interdisciplinary in nature and involves one or more postdoctoral and graduate students, who receive excellent training in preparation for careers in industry, government laboratories or academia. %%% This basic experimental research project deals with the behavior of superconductors which are not in the ideal lossless supercurrent state. Electrical resistance can arise in a Type II superconductor subjected to current flow and to an external magnetic field. In this case a Hall voltage of a puzzling nature can be observed, and is a focus of the present research. A second regime of interest in the present work occurs for temperatures close to the critical transition temperature, where fluctuation effect s will be studied. The work is primarily carried out on high Tc materials. The Hall effect will be studied in NCCO and PCCO superconductors of varying stoichiometries, in order to determine whether the anomalous sign change of the Hall effect arises from vortex pinning or from charge acquired by the vortices. The Hall effect and vortex correlations will also be studied using a Giaever flux transformer, which provides coupling between two vortex systems. The fluctuation effects are characterized with a comprehensive set of measurements, from DC current-voltage characteristics, to mutual inductance measurements up to 100kHz, to microwave response measurements. These measurements will be done in thick (3-D) YBCO samples as well as in progressively thinner samples, so that the crossover to 2-D can be studied. This research program is interdisciplinary in nature and involves one or more postdoctoral and graduate students, who receive excellent training in preparation for careers in industry, government laboratories or academia. ***

W：\ Awards \ Awards96 \*。Doc 9732800 LOBB这个实验研究项目涉及超导体的动态性能，重点是高TC材料。将在NCCO和不同石术学的PCCO超导体中进行研究，以确定霍尔大厅效果的异常符号变化是由涡旋固定引起的还是涡流获得的电荷。还将使用GIAEVER FLUX变压器研究大厅效应和涡流相关性，该变压器在两个涡流系统之间提供耦合。当在零场中超导正常过渡附近的波动导致时变阶段时，将会研究第二个动力学状态。与此过渡相关的关键指数参数将通过一组全面的测量值进行探测，从直流电流 - 电压特性到最高100kHz的相互电感测量到微波炉响应测量。这些测量将以厚（3-D）的YBCO样品以及逐渐较薄的样品进行，因此可以研究交叉到2-D。该研究计划本质上是跨学科的，涉及一名或多个博士后和研究生，他们接受了为工业，政府实验室或学术界的职业做准备的出色培训。 %%％这些基本的实验研究项目涉及不在理想的无损超流状态的超导体的行为。在经电流流量和外部磁场的II型超导体中可能出现电阻。在这种情况下，可以观察到令人困惑的性质的大厅电压，并且是本研究的重点。对于接近临界过渡温度的温度，将发生在当前工作中的第二个感兴趣，其中将研究波动效应。这项工作主要是在高TC材料上进行的。为了确定大厅的效果的变化是由涡流的异常变化效应是由涡流固定引起的还是涡流获得的涡流效应是在变化的石化效果上的NCCO和PCCO超导体中研究大厅效应。还将使用GIAEVER FLUX变压器研究大厅效应和涡流相关性，该变压器在两个涡流系统之间提供耦合。波动效应的特征是一组从直流电流 - 电压特性到高达100kHz的相互电感测量到微波炉响应测量值的全面测量值。这些测量将以厚（3-D）的YBCO样品以及逐渐较薄的样品进行，因此可以研究交叉到2-D。该研究计划本质上是跨学科的，涉及一名或多个博士后和研究生，他们接受了为工业，政府实验室或学术界的职业做准备的出色培训。 ***