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

这个项目将研究强库仑相互作用和随机静电势之间的相互作用，这是凝聚态物理的中心问题之一。众所周知，在非相互作用或弱相互作用电子的二维系统中，无处不在的随机环境导致了绝缘基态。然而，在过去的十年里出现了新的证据，表明在强相互作用电子的二维系统中，从绝缘相到金属相的转变，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“只是金属”的二维电子和空穴系统的热力学数量。具体地说，将使用一种新开发的技术来研究强相互作用电子(空穴)的轨道和自旋磁化。这些实验将在超净硅MOSFET中进行，以及在其他低无序的二维系统中进行：p型和n型SiGe异质结。这些实验将伴随着敏感的超低温输运测量，如平行磁阻和舒布尼科夫-德哈斯测量。预计这一结果将极大地加深我们对二维金属-绝缘体转变的理解。另一个影响将是对教育，因为这个项目将为学生提供一个很好的介绍前沿领域物理学研究的机会。它将纳入东北大学著名的本科生合作教育计划。强大的库仑相互作用和随机势之间的相互作用一直是凝聚态物理学中的一个长期问题。在过去的十年里出现了新的证据，表明在超低温下，电子之间的强相互作用可能会稳定二维系统中的金属状态。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。这项拟议的研究是理解这一重要问题的持续实验努力。预期的实验结果将提高基础知识，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，众所周知，基于半导体的量子计算和自旋电子学等新技术领域严重依赖这种知识。另一个影响将是对教育，因为这个项目将为学生提供一个很好的介绍，让他们在物理学的前沿开展研究。该项目将为研究生和本科生在学术界、工业界和政府的职业生涯做好极好的准备。

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.