Quantum Many - Body Effect of Two - Dimensional Electron Systems on Helium Films

氦薄膜上二维电子系统的量子多体效应

基本信息

批准号：
14340110
负责人：
SHIRAHAMA Keiya
金额：
$ 8.58万
依托单位：
Keio University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

项目摘要

We have investigated a two - dimensional (2-D) electron system formed on a superfluid helium film. A variety of novel quantum phenomena such as quantum melting of the Wigner crystal, a low - density quantum fluid state and its quantum Hall effects have been expected for the electrons on high - dielectric constant materials. However, experiments have failed to realize stable 2-D electrons. In this study we have attempted to form 2-D electrons and to make conductivity measurement. The results are summarized as follows:1. We have made and constructed a dilution refrigerator, a ^4He cryostat, and a AC conductivity measurement setup. We have developed a novel conductivity cell, in which the height of helium surface is controlled by a piezoelectric motor. This makes a fine thickness. We have employed an atomically flat sapphire substrate (dielectric constant 〜9). We have succeeded to form the very low density electrons, and taken conductivity data in a wide range of temperature.2. In order to control the coupling of the electrons to helium surface excitations (ripplons), we have conducted the conductivity measurement for electrons on ^3He - ^4He liquid mixtures. We have quite unexpectedly observed resonance phenomena under perpendicular magnetic field. We have revealed that the resonances result from an inhomogeneity of electron density, and the addition of ^3He atoms to liquid ^4He enhances and stabilizes the density inhomogeneity.We have observed an anomalous nonlinear transport phenomenon in the 2-D Wigner crystal on liquid ^3He revealed theoretically that the nonlinearity is attributed to a strong damping effect inherent in liquid ^3He. This finding gives an important clue for future experiments on electrons on ^3He films at ultraslow temperatures.

我们已经研究了在超氟氦膜上形成的两个尺寸（2 -D）电子系统。预计电子在高 - 旧的恒定材料上，已经预计各种新型量子现象，例如Wigner晶体的量子熔化，低密度量子流体状态及其量子厅效应。但是，实验未能实现稳定的二维电子。在这项研究中，我们试图形成二维电子并进行电导率测量。结果总结如下：1。我们制造并构建了稀释冰箱，A ^4HE低温恒温器和AC电导率测量设置。我们已经开发了一个新型的电导率电池，其中氦表面的高度由压电电动机控制。这使得厚度很好。我们采用了原子蓝宝石底物（介电常数〜9）。我们已经成功地形成了非常低的密度电气，并以广泛的温度获取了电导率数据2。为了控制电子与氦表面兴奋的耦合（瑞氏），我们对 ^3he- ^4he液体混合物的电子进行了电导率测量。在垂直磁场下，我们意外地观察到了共振现象。我们已经揭示了这种共振是由电子密度的不均匀性引起的，并且将 ^3he原子添加到液体中 ^4e ^4e的加强并稳定密度不均匀性。我们已经观察到一种异常的非线性传输现象，在液体 ^3He的液体效果上，在液体上揭示了液体的效果，这是一种异常的效果。 ^3he。这一发现为在超声温度下的 ^3he膜上的电子上进行了将来的实验提供了重要的线索。