Novel Phases and Quantum Phase Transitions in Quantum Hall Effect

9701426徐这项研究是在半导体物理领域，探索在极高迁移率半导体设备中形成二维气体的电子的行为。研究领域是量子霍尔效应(QHE)和分数量子霍尔效应。在最近的研究中，PI对二元对称性的实现做出了贡献。这项研究旨在探索QHE液相和新发现的绝缘相之间的二元对称性。另一个要研究的课题是液体到绝缘体转变过程中纵向和横向导电性之间的普遍关系。在迁移率极低的样品中，提出了另一类跃迁。这个研究项目对最先进的半导体器件中传导电子的行为进行了实验研究。研究发现，在低温强横向磁场条件下，极纯半导体样品中的传导电子在近二维的平面区运动时，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产生的基本效应，这些效应适用于通过库仑排斥相互作用的致密电子气体。人们期待着新的行为，被描述为电子气的新相，本研究致力于发现和描述这些新行为。所获得的理解可望有助于微电子设备技术的改进。***

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. ***