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

Princeton University, Princeton NJ

Investigators

Abstract

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.