Strongly Correlated Electron Phenomena in Rare Earth and Actinide Intermetallics

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Technical: In rare earth and actinide materials, hybridization between localized f-electron and conduction-electron states yields novel phenomena such as heavy fermion behavior, non-Fermi liquid behavior, Kondo insulating behavior and superconductivity. The objectives of this research program are to characterize unconventional electronic ordered phases found in f-electron materials, determine the conditions under which they are formed, identify underlying microscopic mechanisms, and test relevant theories. These goals are sought experimentally through the measurement of the transport, thermodynamic, and magnetic properties of single crystals and thin films of novel rare earth and actinide compounds at low temperatures (down to the mK range), high magnetic fields, and high pressures. This investigation features three main thrusts: non-Fermi liquid behavior, unconventional superconductivity and other ground states, and the search for new correlated electron materials. Materials currently at the core of these studies include the CeMIn5 compounds, the Pr-based filled skutterudites, and U-based intermetallics such as URu2Si2. The study of strongly correlated electron phenomena in this laboratory serves to train the next generation of condensed matter and materials physicists who will contribute to academic, industrial, and governmental arenas throughout their careers. In addition to improving basic understanding of correlated electron behavior, these studies may also directly lead to technological advances such as thermoelectric refrigeration and magnetic information storage.Non-technical:The objective of this research program is to experimentally characterize the class of unusual strong interactions between electrons referred to as "correlated electron" behavior. Correlated electrons lead to a variety of interesting effects, such as superconductivity and unconventional magnetism. These phenomena are often observed in "f-electron" materials, those composed of rare earth or actinide elements, which include cerium and uranium. This investigation encompasses the synthesis of these f-electron materials and the subsequent experimental measurement of their electrical and magnetic properties. Via this approach, the different types of behavior attributed to correlated electron effects will be analyzed with the goal of better describing these effects and ultimately understanding the various conditions under which they occur. This investigation further involves a search for new materials exhibiting correlated electron behavior. This program serves to train the next generation of condensed matter and materials physicists who will contribute to academic, industrial, and governmental arenas throughout their careers. In addition to forming a deeper understanding of correlated electronic behavior, the knowledge developed from these studies may also lead to new advanced sensors, devices, and technologies for use in the energy, information, environmental, medical, and defense sectors.