Acquisition of Instrumentation for Cooling Semiconductor-based Low-Dimensional Electron Systems to T~1mK in a Large Magnetic Field

该补助金提供资金，用于购买加州理工学院的仪器，用于研究半导体中的低维相关电子系统。该仪器将允许在低至1毫开尔文的低温下研究这些系统，这比目前的做法低十倍。此外，该仪器将允许在低温下对样品施加高达16特斯拉的大磁场。在1毫开尔文或接近1毫开尔文的温度下工作的需要与可用的半导体异质结构样品的质量和复杂性的稳步提高有关。这一趋势导致了无数次遇到微妙的电子相关现象，其彻底的研究需要比使用传统的氦稀释制冷更低的温度。在1毫开尔文附近需要研究的现象中，突出的是所谓的偶分母分数量子化霍尔效应;最近发现的，但未预测的，在第一激发朗道能级的二维电子气的绝缘相;以及双层电子气在强耦合极限中的显着性质。后者特别有趣，因为它开始显得好像这个系统是一个长期预测但难以捉摸的集体状态的例子，称为激子超流体。当稀释制冷的技术限制被新仪器所解除时，有可能会有新的发现。这台仪器的购置将对加州理工学院的研究生和本科生的教育产生影响。研究生，为了攻读博士学位。学位，将能够执行实验，在低维相关电子系统的研究前沿。学生将获得在低温/高磁场制度下工作所需的非常先进的实验技术的经验。这种技术经验将帮助他们成功地在学术，国家实验室和工业环境中竞争工作。本科生，通过两个夏季时间的研究和研究参与课程在学年期间，也将能够与这种新的仪器。建立一个最先进的设备，用于在1毫开尔文温度范围内研究相关电子物理的前景已经引起了小组学生的想象。代表性不足的少数民族和女性研究人员（包括研究生和本科生）参加了国家科学基金会资助的研究，他们的参与将继续下去。这种新的仪器将为这些学生提供重要的机会。

This grant provides funding to acquire instrumentation at the California Institute of Technology for research on low-dimensional correlated electron systems in semiconductors. The instrumentation will allow the investigation of these systems at low temperatures down to 1milliKelvin, a factor of ten below current practice. In addition, the instrumentation will allow large magnetic fields, up to 16 Tesla, to be applied to the samples at low temperatures. The need to work at, or near the temperature of 1milliKelvin is related to the steady improvement in the quality and complexity of the semiconductor heterostructure samples that are available. This trend has led to numerous encounters with subtle electron correlation phenomena whose thorough study demands lower temperatures than are available using conventional helium dilution refrigeration. Prominent among the phenomena requiring study near 1milliKelvin are the so called even-denominator fractional quantized Hall effects; the recently discovered, yet unpredicted, insulating phases of the 2 dimensional electron gas in the first excited Landau level; and the remarkable properties of bilayer electron gases in the strongly coupled limit. The latter is particularly interesting since it is beginning to appear as if this system is an example of a long-predicted, yet elusive, collective state known as an excitonic superfluid. There is the possibility of new discoveries when the technical limitation of the dilution refrigeration is lifted by the new instrumentation.This instrumentation acquisition will have impact the education of graduate and undergraduate students at Caltech. Graduate students, in pursuit of their Ph.D. degrees, will be able to perform experiments that are at the cutting edge of research on low-dimensional correlated electron systems. Students will become experienced with the very advanced experimental techniques needed to work in the low temperature/high magnetic field regime. This technical experience will help them successfully compete for jobs in the academic, national lab, and industrial environments. Undergraduate students, through both summer time research and research participation courses during the academic year, will also be able to work with this new instrumentation. The prospect of establishing a state-of-the-art apparatus for pursuing correlated electron physics into the 1milliKelvin temperature regime has already caught the imagination of the students in the group. Underrepresented minority and female researchers (both graduate and undergraduate students) have participated in the NSF-funded resarch and their participation will continue. This new instrumentation will provide important opportunities for these students.