Understanding Correlated Electron Ground States: The Magnetic/Superconducting Boundary in Heavy Fermions

该项目研究了一组等电子、同构的致密近藤化合物，这些化合物显示了高度相关电子系统的广泛基态：磁性、超导性和没有其他顺序的重费米子。使用温度，压力和外加磁场的变量来研究致密和稀释系统，可以根据晶格近藤尺度来表征致密近藤材料，该晶格近藤尺度在低温下从单离子近藤尺度演变而来。这种表征提供了相关电子系统的分类，它可以首次提供一个框架，用于理解在相关电子系统中发现的基态的强烈变化，这些系统在其物理学中与技术感兴趣的不太简单的过渡元素化合物密切相关。这项研究的一个现实目标是第一次精确地描述什么是“重费米子”，并显示它如何转移到d带元素。高中生，大学本科生和研究生将接受培训，以使用材料的广阔相空间作为材料驱动凝聚态研究中的有效和强大的变量。处于磁性和非磁性之间的金属材料通常在低温下发展出不寻常的电子特性，并且可以显示出与高温超导性相关的令人惊讶的超导性。本研究项目试图通过使用高压和高磁场研究一组密切相关的化合物来回答这一问题，这些化合物含有稀土元素铈沿着其他金属，在低温下显示出各种有趣的特性。这些结果有望首次为这些材料的物理学带来一个清晰的秩序，这可以为技术上重要的过渡元素化合物的更复杂的物理学提供新的见解并提出新的研究方向。从高中到研究生水平的学生将通过新材料单晶生长的培训来介绍凝聚态物理，为真正理解固体如何工作提供有价值的基础。

This project studies an isoelectronic, isostructural set of dense Kondo compounds which display a broad spectrum of ground states of highly correlated electron systems: magnetism, superconductivity and heavy Fermion without other order. Using the variables of temperature, pressure and applied external magnetic field to study both the dense and diluted systems, it is possible to characterize dense Kondo materials in terms of a lattice Kondo scale which evolves at low temperature from the single ion Kondo scale. This characterization provides a classification of correlated electron systems which can provide for the first time a framework for understanding the strong variation of ground states found in correlated electron systems, systems which are closely related in their physics to the less simple transition elements compounds of technological interest. A realistic goal of this study is to give for the first time a precise description of what a "heavy Fermion" is and show how this carries over to d-band elements. High school students, college undergraduates and graduate students will be trained to use the broad phase space of materials as an effective and powerful variable in materials driven condensed matter research.%%%%Metallic materials on the border between magnetism and non-magnetism develop unusual electronic properties, usually at low temperature, and can display a surprising type of superconductivity that appears related to high temperature superconductivity. This research project attempts to answer how this comes about through a study using high pressure and high magnetic field to investigate a closely related set of compounds containing the rare earth element Cerium along with other metals, which display a broad variety of interesting properties at low temperature. The results hold the promise to bring for the first time a clean order to the physics of these materials which can provide new insights and suggest new research directions in the more complicated physics of technologically important transition element compounds. Student from high school to graduate level will be introduced to condensed matter physics through training in the growth of single crystals of new materials, providing a valuable underpinning for really understanding how solids work.