RUI: Magnetic and Superconducting Properties of Nickel Borocarbides

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Technical :This award will support our continuing efforts to study the coexistence and competition between magnetism, superconductivity, and heavy fermion behavior in the rare-earth nickel-borocarbides and some related systems. We will continue to measure thermal expansion and magnetostriction using a new capacitive dilatometer developed by the PI (and now in regular use at Los Alamos National Laboratory, Ames Laboratory, and the National High Magnetic Field Laboratory). These measurements will allow us to map out phase diagrams and thermodynamically characterize phase transitions between the low temperature states of these materials. Our measurements will also be combined with existing specific heat measurements in a Gruneisen analysis that will characterize the volume dependence of the characteristic energies of these fascinating materials. Undergraduates, drawn from a diverse pool of talented students, will participate in all aspects of this work, from installing samples, acquiring and analyzing data to assisting during research trips to our collaborators and their institutions.Non-Technical:From electric motors to high-capacity disk drives, magnetic materials are an intrinsic component of our increasingly technological society. Superconductivity, on the other hand, holds the promise of significant technological advancement in areas as diverse as power transmission and high speed transportation. Magnetism and superconductivity are usually mutually exclusive, so the study of materials in which both phenomena coexist and compete is important for understanding the basic physics involved and for finding new kinds of superconducting and magnetic states. This project will support our continuing efforts to study these phenomena with measurements of the thermal expansion using a new capacitive dilatometer developed by the PI (and now in regular use at Los Alamos National Laboratory, Ames Laboratory, and the National High Magnetic Field Laboratory). These measurements will allow us to better understand the competing interactions that underlie these important states of matter, to map out phase diagrams, and to thermodynamically characterize the transitions between the low temperature phases. Undergraduates drawn from a diverse pool of talented students at Occidental College (a small liberal arts college in Los Angeles) will participate in all aspects of this work, both in our on-campus laboratory and during research trips to work with our collaborators at their home institutions. In this way our students will be exposed to the environments of both "small" and "big" science.