Crystal structures and low-temperature behaviors of the heavy-fermion compounds CeRuGe{sub 3} and Ce{sub 3}Ru{sub 4}Ge{sub 13} containing both trivalent and tetravalent cerium
- Tata Institute of Fundamental Research, Bombay 400005 (India)
- Ames Laboratory and Department of Materials Science and Engineering, Iowa State University, Ames, Iowa 50011-3020 (United States)
- University of Missouri Research Reactor, Columbia, Missouri 65211 (United States)
Two different samples of the Ce-Ru-Ge ternary system of nearly the same composition, Ce{sub 3}Ru{sub 4}Ge{sub 13} and CeRuGe{sub 3}, have been studied, as well as the compound Y{sub 3}Co{sub 4}Ge{sub 13}, which contained a nonmagnetic rare earth as the reference material. Combined x-ray and neutron-diffraction studies of CeRuGe{sub 3} and an x-ray study of Ce{sub 3}Ru{sub 4}Ge{sub 13} show that we are dealing with internally distorted (probably 3D modulated) crystals with variable composition, i.e., Ce{sub 4{minus}{ital x}}Ru{sub 4}Ge{sub 12+{ital x}} and ranging from at least {ital x}=0 (1:1:3) to {ital x}=1 (3:4:13). We have measured the dc magnetic susceptibility, the ac susceptibility, the zero-magnetic-field heat capacity, the magnetic heat capacity in fields ranging from 0 to 9.85 T, and the electrical resistivity. The paramagnetic susceptibility and x-ray crystallography data indicate that the Ce{sub 4{minus}{ital x}}Ru{sub 4}Ge{sub 12+{ital x}} alloys cotain both trivalent cerium and tetravalent cerium in a 1 to 3 ratio. As far as we are aware, this is the first time such a valence situation has been reported for a cerium compound. In addition, the heat-capacity results show that Ce{sub 4{minus}{ital x}}Ru{sub 4}Ge{sub 12+{ital x}} is a heavy fermion with {gamma} varying from 428 to 592 mJ/mol Ce{sup 3+}K{sup 2} at the 1:1:3 and 3:4:13 compositions, respectively. Zero-field and magnetic-field heat capacity, and ac magnetic susceptibility data suggest that CeRuGe{sub 3} is a spin-glass system below {similar_to}5 K, which is consistent with the specific features of its crystal structure. Y{sub 3}Co{sub 4}Ge{sub 13} displays normal metallic behavior.
- Research Organization:
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 122977
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 52, Issue 10; Other Information: PBD: 1 Sep 1995
- Country of Publication:
- United States
- Language:
- English
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