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STUDY OF DENSE KONDO COMPOUNDS WITH HIGH KONDO TEMPERATURE.

高近藤温度下的致密近藤化合物的研究。

基本信息

批准号：
61460036
负责人：
ISIKAWA Yosikazu
金额：
$ 3.97万
依托单位：
TOYAMA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1986
资助国家：
日本
起止时间：
1986 至 1987
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-61460036/
关键词：
Kondo effect dense Kondo compound heavy electron valence mixing intermediate valence Czochralski pulling method single crystal 単結晶【La_(1-x)】CexNi 電気抵抗低温比熱

项目摘要

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.

实验研究了La_ Ce_xNi的基本性质<l-x>，其中Ceni是一种致密的近藤化合物，具有很高的近藤温度。电阻率、晶格常数、磁化率和比热的实验结果表明，CeNi化合物是一种致密的近藤化合物，具有很高的近藤温度。La_ Ce_xNi系统的近藤温度<l-x>随Ce原子浓度从0增加到1而在4 ~ 100 K之间连续变化。实验结果表明，SmCu_2是一种反铁磁体，其Neel温度为23 K，并在考虑反铁磁交换作用的Sm三价离子改进的点电荷模型的基础上，很好地解释了各向异性磁化率的温度依赖性。然而，磁熵估计为Rln 2的88%。低温下的混合价态是不被否定的，本项目的主要内容之一是用提拉法制备致密的近藤化合物和混合价化合物的纯单晶样品。我们用80%的科研补助金购买了一台单晶炉。我们已经成功地拉制出LaNi、CeNi、SmCu_2、LaInCu_2、CeInCu_2和SmInCu_2等单晶。采用固相电输运法提纯LaNi和CeNi，用于即将进行的德哈斯-范阿尔芬效应实验。