CAREER: Generic Phase Diagram of the Mixed State of Type IISuperconductors

w：\awards\awards96\num.doc 9702535 Safar 这个实验性的CAREER资助项目关注相图 描述 的 通量 渗透 在 类型 II超导体。 PI发现了固液相变 的磁通晶格中所经历的 铜氧化物超导体激发了对该相图的II型超导体的更普遍的研究。特别令人感兴趣的是各向异性，无序和热涨落对创造新观察到的涡旋液体和II型超导体的相关状态的影响。 实验将测量温度和磁场的依赖性的线性和非线性磁电阻所产生的磁通量运动。此外，临界电流和能量势垒（激活能）将被测量。磁通-流量电压的实验测量将覆盖非常宽的电压动态范围：使用定制的基于SQUID的电压表的亚微伏到纳伏范围，以及使用最先进的商用电压表的纳伏到毫伏范围。要研究的材料包括铜酸盐和传统的层状超导体。拟议的研究将纳入教育计划，以帮助提高 学生学习和培养未来 科学家，包括代表性不足的少数群体成员。 %这个CAREER资助项目涉及基础实验研究 关于磁场与 超导 状态 它专注 对 的 类型 II型超导体比I型超导体对磁场更耐受，因为磁场可以以量子化通量线或涡旋的形式穿透II型超导体，而不一定破坏零电阻状态。 当电流密度对磁通线施加足够强的力使磁通线移动时，第二类超导体中会出现电阻，从而产生热效应。因此，该研究领域与超导体在涉及高电流和高磁场的应用中的电流处理能力有关，例如电力电缆和电动机或发电机中的绕组。在这方面的一个新现象，即量子化通量线的熔化或类液体运动，是近几年在高跃迁中发现的 高温铜氧化物超导体， 这 特别有希望用于载流电缆中。 因此，该项目中进行的基础研究有望长期促进电力技术的改进。 研究 将 将这些建议纳入教育计划，以帮助提高学生的学习水平，培养未来的科学家，包括代表性不足的少数群体成员。 ***

w:\awards\awards96\num.doc 9702535 Safar This experimental CAREER grant project focuses on the phase diagram describing the flux penetration in Type II superconductors. The discovery by the PI of the solid-liquid transition undergone by the flux lattice in the cuprate superconductors spurs investigation more generally among Type II superconductors of this phase diagram. Of particular interest are the effects that anisotropy, disorder and thermal fluctuations have on creating the newly observed vortex liquid and related states of the Type II superconductor. The experiments will measure the temperature and magnetic field dependencies of the linear and nonlinear resistivities which arise by flux motion. In addition, the critical currents, and energy barriers (activation energies) will be measured. The experimental measurement of flux- flow voltages will cover a very broad voltage dynamic range: sub- picovolt to nanovolt range using a custom-built SQUID-based voltmeter, and from nano to millivolts using state of the art commercial voltmeters. The materials to be studied include both cuprate and conventional layered superconductors. The proposed research will be integrated into an education plan to help enhance student learning and to train future scientists, including members of under-represented minority groups. %%% This CAREER grant project involves fundamental experimental research on the interaction of magnetic fields with the superconducting state. It is focused on the Type II superconductors, which are more tolerant of magnetic field than Type I superconductors, in that magnetic field can penetrate the Type II superconductor in the the form of quantized flux lines or vortices, without necessarily destroying the zero resistance state. Electrical resistance, and therefore heating effects, occur in Type II superconductors when the current density, exerts a sufficiently strong force on the flux lines to cause them to move. This field of research therefore is relevant to the current handling capacity of superconductors in applications involving high currents and high magnetic fields, such as electric power cables and windings in motors or generators. A new phenomenon in this connection, melting or liquid-like motion of the quantized flux lines, has been discovered in the past few years in the high transition temperature cuprate superconductors, which are particularly promising for applications in current carrying cables. The fundamental research carried out in this project therefore is expected to contribute in the long term to an improved electric power technology. The research will be integrated into an education plan to help enhance students learning and to train future scientists, including members of under-represented minority groups. ***