Studies with Liquid Helium Films

液氦薄膜研究

• 批准号: 0138009
• 负责人: Robert Hallock
• 金额: $ 30万
• 依托单位: University of Massachusetts Amherst
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-03-15 至 2007-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0138009&HistoricalAwards=false
• 关键词: Studies; Liquid; Helium; Films

This low temperature project seeks to understand the unique properties of helium films and to use these films to address problems of interest in Condensed Matter Physics. A primary objective is to study new aspects of the He-3-He-4 mixture film system. This work would include confirmation of two-dimensional Fermi liquid parameters and a search for a new superfluid state in the two dimensional 3He atop a 4He film at very low temperatures. Experiments are also conducted with helium films on patterned substrates in one and two dimensions. Topics of interest include two-dimensional localization and a possible shift of universality class due to an implied film flow. Experimental techniques include quartz crystal microbalance resonance, heat capacity studies of the thermal properties of He-4 and He-3-He-4 mixture films, and third sound studies of helium films on patterned substrates. In addition to contributing to progress in understanding the behavior of helium films themselves, the work has relevance to phenomena such as Fermi systems, localization, and two-dimensional phase transitions. It also provides excellent training for graduate students and undergraduates. The students gain experience in cutting edge technology and fundamental concepts that prepare them for careers in academe, government or industry.This research investigates the remarkable properties of liquid helium. Such study provides unique insights into nature that are not available by the study of any other substance. Study of the wave character of thin helium films on surfaces, that have been deliberately patterned, allows an enhanced understanding of how waves can be trapped in novel environments and of how an imposed flow can modify this behavior. The study of thin film mixtures of the two naturally occurring forms of helium is motivated by theoretical suggestions that a new kind of superfluid film may be found. These studies with mixture films also allow insight into the physics of two-dimensional systems. Students involved in this work gain hands-on research experience with sophisticated instrumentation. This training prepares them for careers in academe, government or industry.

这个低温项目旨在了解氦膜的独特特性，并使用这些薄膜来解决凝结物理学感兴趣的问题。一个主要目的是研究He-3-He-4混合膜系统的新方面。 这项工作将包括确认二维费米液体参数，并在非常低的温度下在4He膜上的两个维度3he中寻找新的超流体状态。 实验还用一个和二维的图案底物上的氦膜进行。 感兴趣的主题包括二维本地化和由于隐含的膜流而导致的普遍性类别的可能转移。 实验技术包括石英晶体微平均共振，HE-4和HE-3-HE-4混合膜的热性能的热容量研究，以及对图案化底物上氦膜的第三次声音研究。 除了促进理解氦膜本身的行为的进展外，这项工作还与诸如费米系统，定位和二维相变的现象相关。 它还为研究生和本科生提供了出色的培训。 学生获得了尖端技术和基本概念的经验，这些概念为学术界，政府或行业的职业做准备。 这样的研究提供了对自然的独特见解，这些研究无法获得任何其他物质的研究。 故意对表面上薄氦膜的波特性的研究，可以增强对如何在新型环境中捕获波和施加的流程如何改变这种行为的波动的理解。 理论上建议可以发现一种新型的超氟膜的理论建议，研究了两种天然形式的氦形式的薄膜混合物的研究。 这些与混合膜的研究还可以深入了解二维系统的物理学。 参与这项工作的学生获得了精致的仪器的动手研究经验。 这项培训使他们为学术界，政府或行业的职业做好了准备。