Calorimetric Study in Single Crystalline RCu_2Si_2 (R: Rare Earth)(Condensed matter: electronic structure and electrical, magnetic, and optical properties)

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Specific heat measurements on a series of ternary compound RCu_2Si_2 (R: La, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tin, Yb, and Lu) single crystals have been performed by the quasi-adiabatic heat pulse method in the wide temperature range from 0.1 to 80K. Almost all the compounds show antiferromagnetic orderings at low temperatures. We found the first-order like very sharp specific heat peaks in RCu_2Si_2 with R=Gd, Tb, Dy, Ho, and Er. Especially, the antiferromagnetic ordering in DyCu_2Si_2 is found to be a first-order transition. From the analyses of the temperature dependence of magnetic entropy, we confirmed that the total splitting energy of the crystalline electric field (CEF) scheme of R^<3+> ion in RCu_2Si_2 is about 100K in all the compounds studied here, except for YbCu_2Si_2. In addition, we observed the nuclear specific heat at low temperatures and estimated the magnitude of internal effective magnetic field H_<eff> at the nucleus.
社団法人日本物理学会の論文
2008-10-15