STUDY OF DENSE KONDO COMPOUNDS WITH HIGH KONDO TEMPERATURE.

点击翻译按钮获取中文摘要

We studied experimentally fundamental properties of La_<l-x>Ce_xNi where Ceni is a dense Kondo compound with a high Kondo temperature. Experimental results of electrical resistivity, lattice constants, magnetic susceptibility and specific heat reveal that the compound of CeNi is one of the dense Kondo compound with a high Kondo temperature although CeNi was heretofore called a mized valence compound. The Kondo temperature of the system La_<l-x>Ce_xNi changes continuously from 4 to 100K as the concentration of Ce atoms increases from zero to one.Motivated by the question whether the intermetallic compound SmCu_2 is a valence mixing compound, we have studied studied the magnetic, transport and thermal properties of SmCu_2 using a purified large single crystal. It is found from these experiments that the compound SmCu_2 is an antiferomagnet with the Neel temperature of 23K and that the temperature dependence of the anisotropic susceptibility is very well nalized on the basis of the modifed point charge model of Sm trivalent ions including the antiferromagntic exchange interaction. The magnetic entropy, however, was estimated to be 88% of Rln2. The mixed valence state at low temperatures is not denied yet.One of the main theme of this project is a sample preparation of purified single crystals of dense Kondo compounds and mixed valence compounds by a pulling mehod. Spending 80%of this Grant-in-aid for Scientific Research, we have purchased an oven for pulling single crystals. We have succeeded to pull single crystals of, for example, LaNi, CeNi, SmCu_2, LaInCu_2, CeInCu2 and SmInCu_2. A solid-state electro-transport method was used to purify LaNi and CeNi for the experiment of de haas-van Alphen effect, which must be done soon.