Acquisition of a Dilution Refrigerator

金属中的电子相互作用可以产生丰富多样的有趣现象，包括超导性、磁有序、重费米子行为、非费米液体行为、近藤效应和价涨落，其中许多现象还没有得到很好的理解。对产生这些现象的微观相互作用的理解所需要的有价值的信息可以从在低温下表现出这些现象的材料的性质的测量中获得。该奖项为稀释制冷机（DR）提供支持，该制冷机将用于测量强相关电子系统的低温特性。DR系统将提供低于10毫开尔文的基础温度，在100毫开尔文时的冷却功率为250微瓦，并提供大量的实验访问。几个附件将添加到基本系统中，包括用于测量混合室下方样品温度的电阻测温仪，以及用于在高磁场中测量的9特斯拉超导磁体系统。在毫开尔文范围内的研究对于一些具有非常低能量尺度的材料尤其重要，包括重费米子超导体、低有序温度磁体、重费米子和近藤化合物，以及那些表现出与量子隧道相关的时间依赖现象的材料。通常，对更低温度的研究产生了意想不到的行为，揭示了与多体基态相关的新的更低能量尺度。这些研究具有基本的科学意义，在开发工业应用的有用材料方面也具有重要意义。

Electronic interactions in metals can produce a rich variety of interesting phenomena including superconductivity, magnetic order, heavy fermion behavior, non-Fermi liquid behavior, Kondo effect, and valence fluctuations, many of which are not well understood. Valuable information needed for developing an understanding of the microscopic interactions that produce these phenomena can be obtained from measurements of the properties of materials that exhibit these phenomena at low temperatures. This award provides support for a dilution refrigerator (DR) which will be used for measurements of low temperature properties of strongly correlated electron systems. The DR system will provide a base temperature of less than 10 milliKelvins with a cooling power of 250 microwatts at 100 milliKelvins, and a large amount of experimental access. Several accessories will be added to the basic system, including resistance thermometry for measuring the temperature of the sample mounted below the mixing chamber, and a 9 tesla superconducting magnet system for measurement in high magnetic fields. Studies in the milliKelvin range are especially important for some materials with very low energy scales including heavy fermion superconductors, low ordering temperature magnets, heavy fermion and Kondo compounds, and those exhibiting time-dependent phenomena associated with quantum tunneling. Very often, investigations to ever lower temperatures yield unexpected behavior, revealing new lower energy scales associated with the many-body ground state. These studies are of fundamental scientific interest and are also of importance in the development of useful materials for industrial applications.