Electrical and Magnetic Properties of Rare Earth Metals and Alloys Subjected to Ultra High Pressures Using Designer Diamond Anvils

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The grant explores the application of recently developed diamond anvil technology to characterize the electrical and magnetic properties of rare earth metals and alloys. A major focus is on the f-delocalization transitions in rare earth systems such as Cerium, Praseodymium, Neodymium, Praseodymium-Neodymium alloys and Samarium, in the pressure range of ambient to 300 GPa and in the temperature range of 10 K to 350 K. The study will develop new understanding of the equation of state and phase transitions in the rare earth metals as well as carbon nanotubes. The central objective of this research is to directly monitor the f-delocalization pressure (loss of permanent magnetic moment on rare earth ions) at ultra high pressures, especially, where no crystallographic volume collapse transitions are known to occur. The research will employ an eight probe designer anvil for electrical conductivity measurements and a designer loop anvil for magnetic susceptibility measurements. A significant goal of this study is to systematically improve the designer diamond anvil technology by critically examining the role of nitrogen impurity in the chemical vapor deposition process. We also envision a new generation of designer diamond anvils with multi-tasking capability. The broader impact of the work is in the involvement of underrepresented minorities and undergraduate students in the high-pressure research.The magnetic susceptibility measurements would provide a sensitive probe for the changes in magnetic order and electrical conductivity measurements would track changes in the electronic and phonon density of states at high pressures. The f-delocalization pressure for the light rare earth metals will provide critical test of the existing Mott transition and Kondo models and further spur theoretical calculations on these systems at high compressions. This research is likely to advance the state of the art in high-pressure research, enabling experiments that were hither-to inaccessible or very difficult.