Two-Dimensional Electrons on Helium

这是一个更新的项目，涵盖了液氦电子研究的四个领域。我们提出了一种新的进入波子极化子态的途径，它由一个自困在表面凹陷中的电子组成。我们认为波纹子诱导的电子弱局域化发生在弱散射极限。当保持电场控制下的散射增加时，将发生向束缚极化子的跃迁，并可能具有很强的局域化，作为束缚态的前兆。电子在低密度极限下的迁移率将作为保持场、磁场和温度的函数来研究。我们将尝试用热波纹和束缚极化子态来观察弱局域化。我们进一步提出研究将电子限制在绝缘衬底中充满氦的凹槽中形成的准一维电子气体的等离子体振荡。我们还将在电子流体中寻找粘弹性模式，并研究被钉住的电子固体作为与钉住中心耦合的函数。这是一个研究液氦表面束缚电子的更新项目。在这种情况下，束缚电子形成一个单层，漂浮在氦的表面上。这个系统是最简单的二维系统。它具有有趣的物理性质，它的一些性质与三维（3D）系统中的性质类似。控制这些类似物的参数可以在更大的范围内变化，并且比在三维空间中更容易控制。我们建议研究氦表面上的电子，试图更好地理解低维系统的物理学和难以探测的三维系统的物理学。我们的研究将包括电子通过随机散射的空间定位，类似于一些3D半导体中的电子定位。通过增加散射率，我们期望发现被困在表面凹陷中的电子，类似于被困在三维高度可压缩晶格中的电子。我们将研究一种模拟三维滑动电荷密度波的钉住电子晶体。我们还建议研究单排电子中的声音，试图理解一维系统的物理学。＊＊＊

9701428 Dahm This is a renewal project covering four areas in the study of electrons on liquid helium. We propose a new route to the ripplonic-polaron state, which consists of an electron self- trapped in a surface dimple. We suggest that ripplon-induced weak localization of the electron occurs in the weak scattering limit. As the scattering, controlled by the holding electric field, is increased, a transition to the bound polaron will occur with possibly strong localization as a precursor to the bound state. The mobility of electrons in the low density limit will be studied as a function of holding field, magnetic field, and temperature. We will attempt to observe weak localization by thermal ripplons and the bound polaron state. We further propose to study plasma oscillations of quasi-one-dimensional electron gas formed by confining electrons to helium filled grooves in an insulating substrate. We will also search for viscoelastic modes in the electron fluid and study the pinned electron solid as a function of coupling to pinning centers. %%% This a renewal project to study electrons bound to a liquid helium surface. In such a situation, the bound electrons form a single layer which floats on the surface of helium. This system is the simplest two-dimensional system. It has interesting physical properties and some of its properties are analogs of those which occur in three-dimensional (3D) systems. The parameters controlling these analogs can be varied through a wider range and are more easily controlled than in three dimensions. We propose to study electrons on a helium surface in an attempt to better understand the physics of systems of lower dimensions and the physics of 3D systems which are difficult to probe. Our study will include the spatial localization of electrons by random scattering, analogous to the localization of electrons in some 3D semiconductors. By increasing the scattering rate we expect to find electrons trapped in surface depressions, an analog of electrons trapped in a highly compressible lattice in 3D. We will study the pinned electron crystal which is an analog of 3D sliding charge-density waves. We also propose to study sound in a single rows of electrons in an attempt to understand the physics of one-dimensional systems. ***