Thermodynamic and Transport Studies of Strongly Interacting Electrons in Two-Dimensional Semiconductors

本项目将研究强库仑相互作用与随机静电势之间的相互作用，这是凝聚态物理的核心问题之一。众所周知，在非相互作用或弱相互作用电子的二维系统中，始终存在的随机环境导致绝缘基态。然而，在过去十年中出现的新证据表明，在强相互作用电子的二维系统中，从绝缘相转变为金属相，并且在转变附近报告了异常的磁性。这些结果启发了大量的实验和理论研究。目前的项目将集中于测量“纯金属”二维电子和空穴系统的热力学量。具体来说，强相互作用电子（空穴）的轨道和自旋磁化将使用一种新开发的技术进行研究。实验将在超净硅mosfet以及其他低无序二维系统中进行：p型和n型SiGe异质结构。这些实验将伴随着敏感的超低温输运测量，如平行磁电阻和舒布尼科夫-德哈斯测量。预计这些结果将大大增加我们对二维金属-绝缘体转变的理解。另一个影响将是在教育方面，因为这个项目将为学生提供一个很好的介绍前沿领域的物理学研究。它将整合东北大学著名的本科生“合作教育”项目。强库仑相互作用与随机势之间的相互作用是凝聚态物理中一个长期存在的问题。在过去十年中出现的新证据表明，在超低温下，电子之间的强相互作用可以稳定二维系统中的金属态。这些结果在科学界引起了极大的关注，并激发了重大的实验和理论活动。拟议的研究是一个持续的实验努力，以了解这个重要的问题。从提议的实验中预期的结果将推进基础知识，并可能对用于高速通信，信号处理，成像和检测的下一代半导体器件的发展产生影响。例如，以半导体为基础的量子计算和自旋电子学等新技术领域都依赖于这种知识。另一个影响将是教育，因为这个项目将为学生提供一个很好的介绍，在物理学的前沿进行研究。该项目将为研究生和本科生在学术界、工业界和政府部门的职业生涯做好准备。

This project will investigate the interplay between strong Coulomb interactions and random electrostatic potentials, one of the central problems in condensed matter physics. It is well known that in two-dimensional systems of non-interacting or weakly interacting electrons, the ever-present random environment leads to an insulating ground state. However, new evidence has emerged within the past decade that indicates a transition from a an insulating to a metallic phase in two-dimensional systems of strongly interacting electrons, with anomalous magnetic properties reported near the transition. These results have inspired numerous experimental and theoretical studies. The current project will focus on measurements of the thermodynamic quantities of "just metallic" two-dimensional electron and hole systems. Specifically, orbital and spin magnetization of strongly interacting electrons (holes) will be studied using a newly developed technique. The experiments will be carried out in ultra-clean silicon MOSFETs, as well as in other low-disordered two-dimensional systems: p- and n-type SiGe heterostructures. These experiments will be accompanied with sensitive ultra-low temperature transport measurements, such as parallel magnetoresistance and Shubnikov-de Haas measurements. It is expected that the results will add significantly to our understanding of the metal-insulator transition in two dimensions. Another impact will be on education, as this project will provide students an excellent introduction to research in forefront area physics. It will incorporate Northeastern's well-known "co-op" education program for undergraduates.The interplay between strong Coulomb interactions and random potentials has been a long-standing problem in condensed matter physics. New evidence has emerged within the past decade indicating that at ultra-low temperatures, strong interactions between electrons may stabilize a metallic state in two-dimensional systems. These results have attracted great attention in the scientific community and have inspired significant experimental and theoretical activity. The proposed research is a continuing experimental effort to understand this important problem. The results anticipated from the proposed experiments will advance basic knowledge, and may have impacts on the development of next generation semiconductor devices for high-speed communications, signal processing, imaging, and detection. For example, the new technological areas such as semiconductor-based quantum computation and spintronics are known to depend heavily on this kind of knowledge. Another impact will be on education, as this project will provide an excellent introduction for students to carry out research at the forefront of physics. The project will give graduate and undergraduate students an excellent preparation for careers in academe, industry, and government.