Magnetotransport and Millimeter Wave Spectroscopy of a Partially Filled Landau Level

9705521 DU这个实验研究项目是研究分数量子霍尔效应下二维电子气的磁输运和毫米波光谱，特别是在部分填充的朗道能级中复合费米子的性质。这些实验为探测量子霍尔系统的动力学开辟了一扇新的窗口。我们将研究束缚态的色散w(Q)和束缚态的固有涨落的内部结构。能量在1-10K之间可调的毫米波将通过表面金属栅或周期性密度调制耦合到二维气体中，并将使用灵敏的差动光导技术进行检测。这些实验还将涉及纳米结构技术，如高分辨率电子束光刻和加工。这个实验研究项目致力于研究导电电子系统在二维平面区域中的基本性质。在低温和高磁场下，这样一组受限的电子显示出一组非常不寻常的特征，在某些方面，相关的实体并不是在真空中表现出来的电子，而是具有可分离的自旋和电荷属性的“准粒子”。这种情况下的“复合费米子”将通过向它们照射无线电波并进行测量来确定它们对无线电波的响应来研究。一方面，这些实验将提供有关电子在低温下在受限层中相互作用时的新的基本信息。另一方面，在这些实验中使用的器件结构与在GaAs工艺中用于先进微电子器件的器件结构相似。这项研究将包括那些在物理领域接受过良好培训并熟悉半导体器件技术的学生，以及那些接受过在工业、政府或教育领域就业的优秀培训的学生。***

9705521 Du This experimental research project is a study of magnetotransport and millimeter wave spectroscopy of the 2-D electron gas in the fractional quantum Hall effect regime, specifically the properties of composite Fermions in a partially filled Landau level. The experiments open a new window to probe dynamics of the quantum Hall system. The internal structure, ie, the dispersion w(q) of the bound states, and the inherent fluctuations of the bound states, will be investigated. Millimeter waves tunable in energy from 1-10K will couple into the 2-D gas via a surface metal grating or periodic density modulation, and a sensitive differential photoconductivity technique will be used for detection. The experiments will also involve nanostructure techniques such as high-resolution electron-beam lithography and processing. %%% This experimental research project is devoted to basic properties of a conducting electron system when confined into a two- dimensional planar region. Such a confined set of electrons at low temperatures and with high magnetic fields exhibits a very unusual set of characteristics, and in some ways the entities which are relevant are not electrons behaving as they behave in vacuum, but "quasi-particles" having separable spin and charge properties. The "composite Fermions" of this situation are to be studied by shining radio waves onto them and making measurments to determine the response to the radio waves. On the one hand the experiments will provide new basic information about electrons when they are in interaction in confined layers at low temperatures. On the other hand the device structures which are used in these experiments are similar to those used in advanced microelectronic devices in the GaAs technology. This research will involve students who will be well trained in the area of physics and will also gain familiarity with semiconductor device technolgy, and who will be excellently trained for employment in industry, government, or education. ***