Studies with Liquid Helium Films

这个低温项目旨在了解氦膜的独特性质，并利用这些膜来解决凝聚态物理学中的问题。主要目的是研究He-3-He-4混合物膜系统的新方面。 这项工作将包括二维费米液体参数的确认和寻找一个新的超流态在二维3 He顶部的4 He膜在非常低的温度。 实验也进行了图案化基板上的氦膜在一个和两个维度。 感兴趣的主题包括二维本地化和一个可能的转变，由于一个隐含的电影流的普适性类。 实验技术包括石英晶体微天平共振，热容量的热性质的He-4和He-3-He-4的混合物薄膜的研究，和第三声的图案化衬底上的氦膜的研究。 除了有助于理解氦膜本身的行为，这项工作与费米系统，局域化和二维相变等现象有关。 它还为研究生和本科生提供了出色的培训。 学生们获得尖端技术和基本概念的经验，为他们在企业，政府或工业中的职业生涯做好准备。这项研究调查了液氦的显着特性。 这种研究提供了对自然的独特见解，这是任何其他物质的研究所无法获得的。 研究表面上的薄氦膜的波动特性，这是故意图案化的，可以更好地理解波如何被困在新的环境中，以及如何施加流可以修改这种行为。 对氦的两种自然存在形式的薄膜混合物的研究是由可能发现一种新的超流膜的理论建议所激发的。这些对混合物膜的研究也使人们能够深入了解二维系统的物理。 参与这项工作的学生获得了使用复杂仪器的实践研究经验。 这种培训为他们在企业，政府或工业中的职业生涯做好了准备。

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.