Interactions and Coherence in Lanthanide Metallic Compounds

9501529菲斯克技术摘要：本项目研究一种新的金属间化合物 镱、铟和铜， 物理性质 这 显示复杂字符 和 对凝聚态物理学领域有重大影响的科学家。该化合物具有一级相变，其中晶格常数和价态不连续地变化，而对称性没有变化。此外，用银取代铟得到的系列化合物还具有新颖的热力学性质。主要研究人员已经成功地完成了生长这些材料的单晶体的艰巨任务，这些材料将通过电阻率、磁化率、热膨胀、弹性常数和中子散射作为温度、压力和磁场的函数来详尽地表征。状态方程将被确定在努力理解的基础上，这些高度相关的电子，或“重费米子”，材料的电子和磁性方面的相变。 %非技术摘要：少数金属表现出类似于气体冷凝成液体的性质：当温度降低到临界温度以下时，密度不连续地变化，晶体对称性没有变化。 这种金属的磁性强度也随之降低。该项目的研究人员最近已经学会了如何生长一种新的金属间化合物的大晶体，这种化合物显示出冷凝行为。 该项目涉及对该化合物及其合金的结构、磁性和电子行为的彻底研究。 目标是了解驱动凝聚的电子之间相互作用的性质，特别是材料的磁性和它的凝聚能之间似乎存在微妙的相互作用。这些研究将提高我们对固体中的电子帮助晶体状态下的原子相干键合的条件的理解。 研究结果可为整个金属物理和磁学领域提供重要信息。

9501529 Fisk Technical Abstract: This project investigates a new intermetallic compound of ytterbium, indium, and copper, with physical properties which display a complex character and whose understanding would have major impact on the field of condensed matter physics. The compound has a first-order phase transition where the lattice constant and valence change discontinuously with no change in symmetry. Additional, novel thermodynamic properties are encountered in the series of compounds obtained by substitution of silver for indium. The principal investigators have succeeded in the difficult task of growing single crystals of these materials which will exhaustively characterized via resistivity, susceptibility, thermal expansion, elastic constants and neutron scattering as a function of temperature, pressure and magnetic field. The equation of state will be determined in an effort to understand the basis for the phase transition in terms of electronic and magnetic properties of these highly correlated electron, or "heavy fermion", materials. %%% Non-Technical Abstract: A small number of metals exhibit a property analogous to the condensation of a gas to a liquid: as the temperature is lowered below a critical temperature, the density changes discontinuously, with no change in crystal symmetry. There is an accompanying decrease in the strength of the magnetism of the metal. The investigators in this project have recently learned how to grow large crystals of a new intermetallic compound displaying the condensation behavior. The project involves a thorough investigation of the structure, magnetism, and electronic behavior of the compound and its alloys. The goal is to understand the nature of the interactions between electrons which drive the condensation, in particular there seems to be subtle interplay between the magnetism of the material and its cohesi ve energy. Such studies will improve our understanding of the conditions under which electrons in solids help to coherently bond the atoms in the crystalline state. The results may provide important information for the entire field of metal physics and magnetism.