Disorder, Localization, and Pinning in Two-dimensional Transport in Intense Magnetic Fields

这是一个实验凝聚态物理项目，将研究在强磁场存在的稀极限下二维电子系统的电荷输运中无序和电子-电子相互作用的作用。该项目将分三个阶段进行：第一阶段需要进行直流输运和微波吸收测量；第二阶段将这些测量扩展到较低的温度，约20毫开尔文；第三阶段进一步将测量范围扩展到微开尔文范围内的超低温。该实验旨在探索二维电子物理的新体系，揭示新量子相背后的现象，并研究它们的相变。该研究为从事具有基础性意义的前沿研究的研究生和博士后提供了特殊的教育机会，这些研究涉及需要超高磁场和超低温的独特实验设施。这种培训使他们能够从事包括学术和工业研究在内的一系列职业。这项研究旨在探索二维电子的物理学，即在低温（在毫开尔文范围内）和高磁场（在2~特斯拉范围内）的极端条件下，在低电子密度极限下，被限制在两种不同半导体之间的界面上的电子片。在这个极限下，电子系统的物理性质是由二维电子之间的相互作用和靠近半导体界面的杂质和缺陷引起的无序所控制的。前者是内在的，后者是外在的，在很大程度上仍然是未知的，难以定量表征。提出的工作集中在二维电子系统的发展，其中相关的无序是已知的和可表征的。它还专注于在新的物理制度下的直流输运和微波吸收实验，以揭示二维电子的新相并研究它们的量子相变。该研究为从事具有基础性意义的前沿研究的研究生和博士后提供了特殊的教育机会，这些研究涉及需要超高磁场和超低温的独特实验设施。这种培训使他们能够从事包括学术和工业研究在内的一系列职业。

This is an experimental condensed matter physics project that will investigate the roles of disorder and electron-electron interaction in the charge transport of two-dimensional electronic systems in dilute limit in the presence of an intense magnetic field. The project will proceed in three stages: the first entails dc transport and microwave absorption measurements; the second stage extends these measurements to lower temperatures, ca. 20 milliKelvin; and the third stage further extends the measurements to ultra-low temperatures in the microKelvin range. The experiments are designed to explore a new regime in two-dimension electron physics and to uncover phenomena underlying new quantum phases, and to investigate their phase transitions. The research provides exceptional educational opportunities for graduate students and post-docs who engage in cutting edge research which is of fundamental significance and which involves unique experimental facilities requiring ultra high magnetic fields and ultra-low temperatures. This training equips them for a range of careers, including academe and industrial research. %%%This research is directed at exploring the physics of two-dimensional electrons, that is a sheet of electrons confined to the interface between two different semiconductors, at the extreme conditions of low temperatures (in the milli-Kelvin range) and high magnetic fields (in the 2~ Tesla range) in the low electron density limit. In this limit, the physics of the electron system is governed by the interplay of the interaction of the two-dimensional electrons among themselves and the disorder caused by impurities and defects close to the semiconductor interface. While the former is intrinsic, the latter is extrinsic and has remained largely unknown and elusive to quantitative characterization. The proposed work is focused on the development of a two-dimensional electron system in which the relevant disorder is known and characterizable. It is also focused on dc transport and microwave absorption experiments in new physical regimes to uncover new phases of the two-dimensional electrons and to investigate their quantum phase transitions. The research provides exceptional educational opportunities for graduate students and post-docs who engage in cutting edge research which is of fundamental significance and which involves unique experimental facilities requiring ultra high magnetic fields and ultra-low temperatures. This training equips them for a range of careers, including academe and industrial research.