Structural Studies on RCu_6(R=Pr,Nd and Sm) at Low Temperatures

概要

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Intermetallic compounds RCu. (R=Pr, Nd and Sm) have phase transitions fromthe structures having orthorhombic symmetries to those of monoclinic symmetries atlow temperatures. The monoclinic angles, '7's, for these compounds have beenmeasured as functions of temperature down to 1.5 K. The p's for PrCu. and NdCu,have monotonic temperature variations that could be reproduced by a simple meanfield theory for the order parameter. The '); for SmCu. was unusual in that ut has amaximum at about 20 K, suggesting the coupling between order parameter and theelectronic states. The temperature dependence of the unit cell volume of SmCu. hasbeen found to exhibit a significant decrease below about 120 K. These results havebeen analyzed on the basis of a coupling of the lattice to a two level system with alevel separation of about 23 K.rare earth compounds, mixed valence, X-ray diffraction
社団法人日本物理学会の論文
1990-11-15