Coherence and Groundstate Properties of Highly Correlated f-Electron System: Kondo Lattice and Heavy Fermion Studies (Materials Research)

这项研究工作的重点是建立一个更好的 对不寻常现象的理解，即，重费米子， Kondo和Kondo晶格，自旋涨落和混合价 行为，这出现在高度相关的f电子系统。 这种现象通常与非定域化有关。 由于f-电子与其他f-电子的杂化， 电子或SPD电子。 高温行为 与这些系统相关的似乎是很好的描述， 单离子模型;然而，在低温下，这些系统 显示出相干的费米液体状行为。 本研究是 旨在研究与此相关的显著特征， 相干基态 测量温度和 电阻率的静水压力依赖性， 比热、磁输运系数和磁 对选定数量的混合价和重金属的敏感性 费米子系统的计划。 这些测量将是 补充的测量温度依赖性的 热电功率和热膨胀沿着与房间 温度晶体结构研究。 的目的 研究的目的是确定间接f-f所起的作用， f-spd交换相互作用和其他因素，如晶体 磁场水平、近藤温度等，在连贯的 国家和长期相关性的性质，例如， 超导性和磁有序性。

This research effort is focused on establishing a better understanding of the unusual phenomena, i.e., heavy fermion, Kondo and Kondo lattice, spin fluctuation and mixed valent behavior, which appear in highly correlated f-electron systems. Such phenomena are commonly associated with a delocalization of the f-electrons due to a f-electron hybridization with other f- electrons or spd-electrons. The high temperature behavior associated with these systems seems to be well described by single ion models; however, at low temperatures these systems display coherent fermi liquid-like behavior. This research is directed at studying the salient features associated with this coherent groundstate. Measurements of the temperature and hydrostatic pressure dependence of the electrical resistivity, specific heat, magneto-transport coefficients and magnetic susceptibility on a select number of mixed valent and heavy fermion systems are planned. These measurements will be supplemented by measurements of the temperature dependence of the thermal electric power and thermal expansion along with room temperature crystal structure studies. The objective of this research is to establish the role played by the indirect f-f and f-spd exchange interactions, and other factors such as crystal field levels, the Kondo temperature, etc., on both the coherent state and on the nature of long range correlations, e.g., superconductivity and magnetic order, within this groundstate.