Thermodynamic Measurements of Collective Phases of Two-Dimensionally Confined Charge Carriers

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。*****非技术摘要****局限于半导体界面的二维电子气体已成为当代凝聚态物理的重要模型系统之一。当主体半导体的无序程度足够低且温度的随机效应降低时，电子可以在丰富多样的有趣相中自由有序。历史上，随着样品质量的不断提高，新的电子相不断被发现。有些阶段已经得到很好的理解，而另一些阶段目前正在加紧调查。与利用电子在系统中的直流电输运的更常见的研究不同，该项目将使用热力学测量来探测已知电子相以前无法获得的性质，并深入了解新发现的奇异相的性质。实验将采用最先进的低温和电子仪器以及现代半导体加工。除了推进我们对这些有趣系统的基本理解之外，这项研究还可能对未来的技术产生影响。该项目将培养一名现代凝聚态物理博士生，并对其进行先进技术培训。在这样一个领域的工作被证明是为从学术界到工业界的大量科学事业做好了极好的准备。本科学生将介绍凝聚态物理的概念和技术。****技术摘要****我们对低维费米子系统的大部分知识来自于对二维电子气体的研究。当受到低温和外部磁场的影响时，这些系统表现出大量的外来电子相。一些相，如整数和分数量子霍尔态和维格纳固体，已被很好地理解。其他如填充因子为偶数的状态也在深入研究中。这个项目将利用热力学测量来探索和阐明限制相关电子的不寻常性质。将采用一种新技术，即在稀释冰箱温度下将系统中的电子与声子解耦。这些测量将对已知但尚未完全理解的阶段产生新的见解，并为最近发现的状态提供信息。本项目将通过现代凝聚态物理的研究和现代半导体加工、低能级测量和低温设备使用方面的培训，为研究生未来的学术或工业生涯提供良好的准备。本科学生将介绍凝聚态物理的概念和技术。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).***** NON- TECHNICAL ABSTRACT ****The two-dimensional electron gas confined to semiconductor interfaces has been one of the important model systems of contemporary condensed matter physics. When the level of disorder in the host semiconductor is low enough and the randomizing effect of temperature is reduced, the electrons are free to order in a rich variety of interesting phases. Historically, with the continuous improvement of sample quality new electronic phases have been discovered. Some phases are well understood while others are currently under intense investigation. Instead of the more common studies utilizing the dc transport of electrons through the system, this project will use thermodynamic measurements to probe previously inaccessible properties of known electronic phases and yield insight into the nature of the newly discovered, exotic phases. The experiments will employ state-of-the art cryogenic and electronic instruments and modern semiconductor processing. Aside from advancing our fundamental understanding of these intriguing systems, this research could have an impact of future technologies. This project will educate a doctoral student in modern condensed matter physics and training in advanced technologies. Work in such a field is proven to be an excellent preparation for a large spectrum of scientific careers from academia to industry. Undergraduate students will be introduced to concepts and techniques of condensed matter physics.****TECHNICAL ABSTRACT****Much of our knowledge of low dimensional fermionic systems comes from studies on two-dimensional electron gases. When subjected to low temperatures and an external magnetic field, these systems exhibit a large number of exotic electronic phases. Some of the phases such as the integer and fractional quantum Hall states and the Wigner solid are well understood. Others such as states with even denominator filling factors are under intense investigation. This project will utilize thermodynamic measurements to explore and elucidate the unusual properties of confined correlated electrons. A new technique will be used which employs the decoupling of the electrons from the phonons in the system at dilution refrigerator temperatures. These measurements will yield new insight into known but not fully understood phases as well as provide information on the most recently discovered states. This project will provide excellent preparation for graduate students for their future academic or industrial careers through the study of modern condensed matter physics and training in modern semiconductor processing, in conducting low level measurements, and in the use of cryogenic equipment. Undergraduate students will be introduced to concepts and techniques of condensed matter physics.