Studies of Two-Dimensional Superconductors and Multilayers in Magnetic Fields

小行星9800663 这项实验性的两名研究人员的研究项目是有关 与 详细 理解 的 二维超导四个研究课题如下： Hc 2附近热力学转变的性质，包括 的 最低有效性 朗道 能级近似 (b)长度刻度 关联 与无序，特别是，比较 与动力学交叉相关的长度与从直流临界电流测量中提取的无序长度（c）超导体-绝缘体转变，重点是可能的 量子 隧穿 的 涡流 在 超导相和屏蔽（从接地层）对过渡性质的可能影响，以及（d）偏置电流对2-D超导体中涡旋系统的影响。 这项工作的很大一部分将涉及多层钼锗合金。该系统已被证明是一个很好的模型系统，在三维到二维交叉效应的研究在超导。这项高度跨学科的研究将涉及研究生和博士后研究人员，他们将接受有益于他们未来在工业，政府或学术界的职业生涯的优秀培训。 这个实验性的两名研究者基础研究项目的重点是当超导体样品接近二维极限时发生的特殊特征。二维样品是这样的样品，其薄到在垂直于样品平面的方向上不发生载流子或电流的运动。该项目将在本质上类似于一副卡片的“超晶格”样品中探测这些性质，其中每张卡片都是超导层，并且在每个导电层之间放置一层薄绝缘层。在这项工作中，两种类型的层通常是钼和锗的合金，其形成合金系统，使得富锗合金是绝缘的，而其他合金成分可以是金属的或超导的。这个系统被选为一个“模型系统”，在其中仔细研究的潜在应用，如铜酸盐超导体的材料中发生的影响。在模型系统中的效果可以更可靠地研究比在铜酸盐。因此，基础研究的结果将导致更好地理解铜氧化物超导性，并可能导致这些材料的新应用。这项高度跨学科的研究将涉及研究生和博士后研究人员，他们将接受有益于他们未来在工业，政府或学术界的职业生涯的优秀培训。 ***

9800663 Kapitulnik This experimental two investigator research project is concerned with detailed understanding of 2-D superconductivity. Four research topics are as follows: (a) The nature of the thermodynamic transition near Hc2, including the validity of the Lowest Landau Level approximation (b) The length scales associated with disorder, and, specifically, comparison of the length associated with crossover of the dynamics with the disorder length extracted from dc critical current measurements (c) The superconductor-insulator transition, with emphasis on possible quantum tunneling of vortices in the superconducting phase and possible effects of screening (from a groundplane) on the nature of the transition, and, (d) The effect of bias current on the vortex system in 2-D superconductors. A substantial portion of the work will involve multilayers of MoGe alloys. This system has proven to be an excellent model system in the investigation of 3-D to 2-D crossover effects in superconductivity. This highly interdisciplinary research will involve graduate student and postdoctoral researchers who will receive excellent training beneficial to their future careers in industry, government or academia. %%% This experimental two investigator basic research project focuses on the special features that occur as superconductor samples approach the limit of being two-dimensional. A two- dimensional sample is one that is so thin that no motion of carriers or electric current occurs in the direction perpendicular to the plane of the sample. The project will probe these properties in samples which are "superlattices" similar in nature to a deck of cards, where each card is a superconducting layer and a thin insulating layer is placed between each conducting layer. In this work the two types of layer will typically be alloys of Molybdenum and Germanium, which form an alloy syst em such that Ge-rich alloys are insulating and other alloy compositions can be metallic or superconducting. This system is chosen as a "model system" in which to carefully study effects that occur in materials of potential for applications, such as cuprate superconductors. The effects can be more reliably studied in the model system than in the cuprates. Thus the results of the basic study will lead to greater understanding of cuprate superconductivity, and may lead to new applications for these materials. This highly interdisciplinary research will involve graduate student and postdoctoral researchers who will receive excellent training beneficial to their future careers in industry, government or academia. ***