Crystal chemistry and magnetic properties of manganese zinc alloy 'YMn{sub 2}Zn{sub 20}' comprising a Mn pyrochlore lattice

Journal Article · Sun Jul 15 04:00:00 EDT 2012 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/J.JSSC.2012.03.038· OSTI ID:22012199

Okamoto, Yoshihiko ^[1]; Shimizu, Takeshi; Yamaura, Jun-ichi; Hiroi, Zenji ^[1]

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1. Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581 (Japan)

The chemical composition, crystal structure, and magnetic properties of a manganese zinc alloy with an ideal composition of YMn{sub 2}Zn{sub 20}, which comprises a pyrochlore lattice made of Mn atoms, are reported. The compound is stable only when In or Al is partially substituted for Zn. We have determined the actual chemical formula as YMn{sub 2+{delta}}Zn{sub 20-x-{delta}}M{sub x}, with M=In or Al, and have identified the characteristic preferences with which the incorporated M and excess Mn{sub {delta}} atoms occupy the three crystallographic sites for Zn atoms. The Mn atoms in the pyrochlore lattice possess small magnetic moments that interact with each other antiferromagnetically but exhibit no long-range order above 0.4 K, probably owing to the geometrical frustration of the pyrochlore lattice. As a result, the effective mass of the conduction electrons is considerably enhanced, as observed in the related pyrochlore-lattice compounds (Y,Sc)Mn{sub 2} and LiV{sub 2}O{sub 4}. However, the presence of excess Mn atoms with large localized magnetic moments comparable to spin 5/2 tends to mask the inherent magnetism of the pyrochlore Mn atoms. It is suggested that 'YMn{sub 2}Zn{sub 18}In{sub 2}' with neither excess Mn atoms nor site disorder would be an ideal compound for further study. - Abstract: Crystal structure of 'YMn{sub 2}Zn{sub 18}In{sub 2}'. Highlights: Black-Right-Pointing-Pointer Two kinds of Mn atoms, pyrochlore Mn and excess Mn, are present in 'YMn{sub 2}Zn{sub 20}'. Black-Right-Pointing-Pointer The excess Mn atom has a large localized moment comparable to that of spin 5/2. Black-Right-Pointing-Pointer The small moment on the pyrochlore Mn may give rise to a heavy-fermion-like behavior. Black-Right-Pointing-Pointer YMn{sub 2}Zn{sub 18}In{sub 2} must be an ideal compound with neither excess Mn nor site disorder.

• OSTI ID: 22012199
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Vol. . 191; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
CHEMICAL COMPOSITION
CRYSTAL LATTICES
CRYSTALS
EFFECTIVE MASS
MAGNETIC MOMENTS
MAGNETIC PROPERTIES
MAGNETISM
MAGNETS
MANGANESE
PYROCHLORE
ZINC ALLOYS