Experimental Study of the Magnetic Flux Line Lattice in Superconductors

w：\awards\awards96\num.doc 9705389 Andrei 这个实验研究项目的重点是量子化磁通线之间的相互作用穿过第二类超导体。有序状态的相互作用通量线，理论上预测的Abrikosov，提供了概念基础的实验工作。物质无序的影响， 热波动和磁通线形成的量子性质导致在Abrikosov晶格变得不稳定的参数区域中的极其复杂的图像。有一些问题与焊剂的玻璃相有关 数组，其中， 寻址 在 这个实验项目。对2 H-NbSe 2的研究确定了通量线晶格的两种状态，其特征在于具有显著不同的动力学，一种是无序的，并且具有比有序晶格高两个数量级的钉扎频率， 并伴随着高得多的临界电流。在这个项目中，局部磁化测量将使用一个阵列的微观霍尔传感器实现的2-D电子气在界面的GaAs/GaAlAs异质结构。其他工作包括直流和交流测量的磁通阵列的剪切模量，和测量的横向电流在动态磁通状态。 部分工作将与魏茨曼研究所的Eli Zeldov博士合作完成。 %这个实验研究项目的重点是第二类超导体在磁场中的行为。在这种情况下，磁场可以穿过超导体，形成量子化的磁通线阵列。在理想的条件下，这些线，每个携带一个量子的磁通量，安排在一个有序的阵列或磁通晶格，理论上预测的Abrikosov。 该实验项目致力于测量在不太理想的条件下，当磁通线可能处于无序状态或处于有点像液体的运动状态时，磁通线的运动和排列。这项研究的结果可能提供的信息的重要性，第二类超导体，包括高温铜酸盐超导体在改进的电气和机电技术的应用。这个研究项目是跨学科的性质，涉及研究生谁将得到良好的培训，进入行业，政府或教育职位。 ***

w:\awards\awards96\num.doc 9705389 Andrei This experimental research project focuses the interactions between quantized magnetic flux lines threading through a Type II superconductor. An ordered state of interacting flux lines, as theoretically predicted by Abrikosov, provides the conceptual basis of the experimental work. The influences of material disorder, thermal fluctuations, and the quantum nature of the flux line formation lead to an extremely complicated picture in the area of parameters where the Abrikosov lattice becomes unstable. There are questions relating to a glassy phase of the flux array, among others, which are addressed in this experimental project. The work on 2H-NbSe2 identified two states of the flux line lattice characterized by dramatically different dynamics, one being disordered and have pinning frequencies two orders of magnitude higher than the ordered lattice, and accompanied by much higher critical currents. In this project local magnetization measurements will be made using an array of microscopic Hall sensors realized in the 2-D electron gas at the interface of a GaAs/GaAlAs heterostructure. Other work includes DC and AC measurements of the shear modulus of the flux array, and measurements of transverse currents in dynamic fluxon states. Portions of the work will be done in collaboration with Dr. Eli Zeldov of the Weizmann Institute. %%% This experimental research project, is focused on the behavior of Type II superconductors in a magnetic field. In this case the magnetic field can penetrate the superconductor, in an array of quantized flux lines. Under ideal conditions these lines, each carrying one quantum of magnetic flux, arrange in an ordered array or flux lattice, as predicted theoretically by Abrikosov. This experimental project is devoted to measurement of the motions and arrangements o f the flux lines in less than ideal conditions when the flux lines may be in a disordered state or in a state of motion somewhat like a liquid. The results of this research may provide information of importance to the application of Type II superconductors including high temperature cuprate superconductors in improved electrical and electromechanical technology. This research project is interdisciplinary in nature and involves graduate students who will be excellently trained to enter positions in industry, government or education. ***