Collaborative Research: Study of Novel Phases in Two Dimensional Electron Systems in High Magnetic Fields and Low Temperature

这个合作研究项目将继续实验，这些实验可能是半导体中二维电子系统中金属-绝缘体(M-I)转变的证据。在一般的理论基础上，许多人认为M-I交易是被禁止的。这些数据暗示着M-I的转变，尽管关于这一主题的理论和实验论文越来越多，但它仍然是一个谜。参与本项目的两个实验小组最近取得的重要进展表明，硅反型层中的M-I转变可能与二维铁磁不稳定性有关。为了测试这一有趣的可能性，将在佛罗里达州盖恩斯维尔由美国国家科学基金会资助的国家高磁场实验室的微开尔文设施中进行超低温和高磁场下的磁阻测量。所寻求的信息对于理解在二维电子气系统中观察到的神秘行为的本质是至关重要的。参与该项目的研究生和本科生将接受涉及尖端技术和半导体器件结构的复杂而重要的前沿物理学领域的培训。这将为他们在工业、政府或教育领域的一系列职业生涯做好准备。这个合作研究项目将研究MOSFET结构中非常高纯度半导体材料的性质，这些材料与目前许多电子设备中的结构有一定的联系。与普遍认为在这种二维半导体中不可能存在金属相的预期相反，最近几年的实验证据表明，可能存在从绝缘行为到金属行为的转变。尽管关于这一主题的理论和实验论文越来越多，但这个问题仍然没有得到解决，并对我们理解电子在半导体中的行为构成了严重的挑战。本项目的主要研究人员一直是这一领域的主要贡献者，并独立地获得了最近的证据，即金属-绝缘体转变可能与铁磁转变的趋势有关。为了测试这一有趣的可能性，将在佛罗里达州盖恩斯维尔NSF支持的国家高磁场实验室的MicroKelvin设施中进行超低温和高磁场下的测量。佛罗里达州盖恩斯维尔。所获得的信息对于理解在二维半导体中观察到的神秘行为的本质是至关重要的。参与该项目的研究生和本科生，包括一些少数族裔学生，将接受涉及尖端技术(包括半导体器件结构)的复杂而重要的前沿物理学领域的培训，这将为他们在工业、政府或教育领域的一系列职业生涯做好准备。

This Collaborative Research Project will continue experiments that may be evidence for a metal-insulator (M-I) transition in two-dimensional systems of electrons in semiconductors. The M-I transtion has been thought by many to be forbidden on general theoretical grounds. The data, which are suggestive of a M-I transition, remains a mystery despite a growing number of theoretical and experimental papers on the subject. Important recent progress, made by two experimental groups involved in the present project, has shown that the M-I transition in silicon inversion layers may be connected with a ferromagnetic instability in two dimensions. To test this intriguing possibility, magnetoresistance measurements will be performed at ultra-low temperatures and high magnetic fields at the MicroKelvin facility of the NSF-supported National High Magnetic Field Laboratory at Gainesville, Florida. The information sought will be crucial for the understanding of the nature of the enigmatic behavior observed in the two-dimensional electron gas systems. Graduate and undergraduate students participating in this project will receive training in a complex and important area of forefront physics involving cutting edge technology and semiconductor device structures. This will prepare them for a range of careers in industry, government or education.This Collaborative Research Project will investigate the properties of very high purity semiconductor materials in a MOSFET structure somewhat related to those found in many current electronic devices. Contrary to the widely-held expectation that no metallic phase is possible in such two dimensional semiconductors, experimental evidence has been obtained in the last few years that indicates there may be a transition from insulating to metallic behavior. The issue remains unresolved despite a growing number of theoretical and experimental papers on the subject, and poses a serious challenge to our understanding of the behavior of electrons in semiconductors. The principal investigators of the present project have been leading contributors to this field, and have independently obtained recent evidence that the metal-insulator transition may be associated with a tendency toward a ferromagnetic transition. To test this intriguing possibility, measurements will be performed at ultra-low temperatures and high magnetic fields at the MicroKelvin facility at NSF-supported National High Magnetic Field Laboratory at Gainesville, Florida. Gainesville, Florida. The information obtained is expected to be crucial for the understanding of the nature of the enigmatic behavior observed in two dimensional semiconductors. Graduate and undergraduate students participating in this project, including some minority students, will receive training in a complex and important area of forefront physics involving cutting edge technology, including semiconductor device structures This will prepare them for a range of careers in industry, government or education.