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

该补助金探索了最近开发的金刚石砧技术的应用，以表征稀土金属和合金的电磁性能。重点研究了稀土系统（如铈、镨、钕、镨钕合金和钐）在环境压力至300 GPa和温度10 K至350 K范围内的f-离域转变。该研究将对稀土金属和碳纳米管的状态方程和相变有新的认识。这项研究的中心目标是直接监测f-离域压力（稀土离子上永久磁矩的损失）在超高压下，特别是在没有晶体学体积塌陷转变的情况下。该研究将采用一个八探针设计砧用于电导率测量和一个设计环砧用于磁化率测量。本研究的一个重要目标是通过严格检查氮杂质在化学气相沉积过程中的作用，系统地改进设计师金刚石砧技术。我们还设想了新一代具有多任务处理能力的设计师金刚石砧。这项工作的更广泛影响是使代表性不足的少数民族和本科生参与高压研究，磁化率测量将为磁序的变化提供灵敏的探针，电导率测量将跟踪高压下电子和声子态密度的变化。轻稀土金属的f-离域压力将为现有的Mott转变和Kondo模型提供关键的测试，并进一步刺激这些系统在高压缩下的理论计算。这项研究可能会推进高压研究的最新技术，使迄今为止无法接近或非常困难的实验成为可能。

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.