Experimental Studies of Metal-Insulator Transitions and Superconductivity

研究了超高磁场下的超导阵列、各向异性超导体、正常金属和二维异质结构。这些研究的最终目的是检验在不同可控电位下是否存在扩展态、局部态和相称态，并对这些状态进行成像，研究它们的动力学。设计用于与穿透磁通晶格相互作用的超导导线网络将使用光刻技术制造。这项工作将侧重于各向异性的影响，其中已经做出了引人注目的理论预测，关于局部化，各向异性可通约性和温度相关的通量晶格构型。体超导体中约瑟夫森涡旋的钉住和动力学将进一步研究。利用高纯度有机超导体，对磁场诱导电子一维化的激动人心的理论预测和由此产生的高磁场下超导性的重建也将进行实验验证。在另一项实验中，基于嵌段共聚物自组装的新型光刻技术将用于在普通金属、超导体和量子霍尔器件上制造“纳米”周期电位（~ 300Ao间距）。这将允许研究一种新的状态，其中周期势与磁长度相当，比许多特征消相和散射长度短得多。将研究超高磁场中的超导阵列、各向异性超导体、普通金属和二维异质结构。具体而言，本研究将解决如何将已被理解的周期势扩展到具有竞争长度尺度和不同类型的异位的准周期势的问题。设计用于与穿透磁通晶格相互作用的超导导线网络将使用光刻技术制造。这项工作将侧重于各向异性的影响，其中已经做出了引人注目的理论预测，关于局部化，各向异性可通约性和温度相关的通量晶格构型。体超导体中约瑟夫森涡旋的钉住和动力学将进一步研究。利用高纯度有机超导体，对磁场诱导电子一维化的激动人心的理论预测和由此产生的高磁场下超导性的重建也将进行实验验证。在另一项实验中，基于嵌段共聚物自组装的新型光刻技术将用于在普通金属、超导体和量子霍尔器件上制造“纳米”周期电位。这将允许研究一种新的状态，其中周期势与磁长度相当，并且比许多特征长度短得多。＊＊＊

9510246 Chaikin Superconducting arrays in very high magnetic field, anisotropic superconductors, as well as normal metals and two dimensional heterostuctures will be studied. The ultimate goal of these studies is to test for the existence of extended, localized and commensurate states in different controllable potentials, to image these states, and to study their dynamics. Superconducting wire networks designed to interact with a penetrating flux lattice will be fabricated using lithographic techniques. This work will focus on the effect of anisotropy where striking theoretical predictions have been made, about localization, anisotropic commensurability, and temperature dependent flux lattice configurations. The pinning and dynamics of Josephson vortices in bulk superconductors will be further investigated. The exciting theoretical prediction of magnetic field induced one dimensionalization of the electrons and the resulting re- establishment of superconductivity at high magnetic field will also be experimentally tested using high purity organic superconductors. In another experiment, novel lithographic techniques based on self assembly of block copolymers, will be used to fabricate "nano" periodic potentials (~ 300Ao spacing) on normal metals, superconductors and quantum Hall devices. This will allow the study of a new regime where the periodic potential is comparable to magnetic lengths and much shorter than many characteristic dephasing and scattering length. %%% Superconducting arrays in very high magnetic field, anisotropic superconductors, as well as normal metals and two dimensional heterostuctures will be studied. Specifically this research will address the question of how the well understood periodic potentials can be extended to quasi-periodic potentials where there are competing length scales and different types of anisot ropy. Superconducting wire networks designed to interact with a penetrating flux lattice will be fabricated using lithographic techniques. This work will focus on the effect of anisotropy where striking theoretical predictions have been made, about localization, anisotropic commensurability, and temperature dependent flux lattice configurations. The pinning and dynamics of Josephson vortices in bulk superconductors will be further investigated. The exciting theoretical prediction of magnetic field induced one dimensionalization of the electrons and the resulting re- establishment of superconductivity at high magnetic field will also be experimentally tested using high purity organic superconductors. In another experiment, novel lithographic techniques based on self assembly of block copolymers, will be used to fabricate "nano" periodic potentials on normal metals, superconductors and quantum Hall devices. This will allow the study of a new regime where the periodic potential is comparable to magnetic lengths and much shorter than many characteristic lengths. ***