Novel Phases and Quantum Phase Transitions in Quantum Hall Effect

[9701426 Tsui]这项研究是在半导体物理领域，探测在极高迁移率的半导体器件中形成二维气体的电子行为。研究方向为量子霍尔效应（QHE）和分数量子霍尔效应。在最近的研究中，π为发现对偶对称性做出了贡献。本研究旨在探索QHE液相与新发现的绝缘相之间的对偶对称性。另一个要研究的课题是QHE液体纵向和横向电导率到绝缘体过渡之间的普遍关系。另一类跃迁是在极低迁移率的样品中提出的。本研究计划实验研究最先进半导体装置中传导电子的行为。研究发现，在极纯半导体样品中，当被限制在近二维平面区域内运动时，在低温和高横向磁场下，导电电子表现出独特的行为方式。这些先前观察到的效应被称为量子霍尔效应和分数量子霍尔效应。它们是由量子力学定律应用于通过库仑排斥相互作用的密集电子气体而产生的基本效应。新的行为被期待，被描述为电子气体的新相，而本研究致力于发现和描述这些新行为。所获得的理解有望有助于微电子器件技术的改进。＊＊＊

9701426 Tsui This research is in the area of semiconductor physics, probing the behavior of electrons forming a 2-D gas in extremely high mobility semiconductor devices. The research is in the area of the Quantum Hall Effect (QHE) and the Fractional Quantum Hall Effect. The PI in recent research has contributed to dicovery of a duality symmetry. The proposed research aims to explore the duality symmetry between the QHE liquid phase and the newly discovered insulating phase. Another topic to be studied is the universal relation between the longitudinal and transverse conductivity in QHE liquid to insulator transition. Another class of transitions is proposed in extremely low mobility samples. %%% This research project experimentally studies the behavior of conduction electrons in state-of-the-art semiconductor devices. It is found that conduction electrons n extremely pure semiconductor samples, when confined to move in a nearly two dimensional planar region, at low temperatures and high transverse magnetic field, behave in unique ways. These previously observed effects are known as the Quantum Hall Effect and the Fractional Quantum Hall Effect. They are basic effects resulting from the laws of quantum mechanics applied to a dense gas of electrons interacting with each other by Coulomb repulsion. New behaviors are expected, described as new phases of the electron gas, and this research is devoted to finding and describing these new behaviors. The understanding gained can be expected to contribute to improvements in microelectronic device technology. ***