Breathing Pyrochlore Lattice Realized in A-Site Ordered Spinel Oxides LiGaCr4O8 and LiInCr4O8

Yoshihiko Okamoto, Gøran J. Nilsen, J. Paul Attfield, Zenji Hiroi

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Abstract

A unique type of frustrated lattice is found in two A-site ordered spinel oxides, LiGaCr4O8 and LiInCr4O8. Because of the large size mismatch between Li+ and Ga3+/In3+ ions at the A site, the pyrochlore lattice, made up of Cr3+ ions carrying spin 3/2, becomes an alternating array of small and large tetrahedra, i.e., a “breathing” pyrochlore lattice. We introduce a parameter, the breathing factor Bf, which quantifies the degree of frustration in the pyrochlore lattice: Bf is defined as J′/J, where J′ and J are nearest-neighbor magnetic interactions in the large and small tetrahedra, respectively. LiGaCr4O8 with Bf∼0.6 shows magnetic susceptibility similar to that of conventional Cr spinel oxides such as ZnCr2O4. In contrast, LiInCr4O8 with a small Bf∼0.1 exhibits a spin-gap behavior in its magnetic susceptibility, suggesting a proximity to an exotic singlet ground state. Magnetic long-range order occurs at 13.8 and 15.9 K for LiGaCr4O8 and LiInCr4O8, respectively, in both cases likely owing to the coupling to structural distortions.

Original languageEnglish
Article number097203
JournalPhysical Review Letters
Volume110
Issue number9
Early online date26 Feb 2013
DOIs
Publication statusPublished - 2013

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