ACTA

New S=1/2 Alternating Chain Compound - High Pressure Form of (VO)₂P₂O_7^-

M. Azuma^a, T. Saito^a, Z. Hiroi^b, M. Takano^a, Y. Narumi^c, and K. Kindo^c
^a Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
^b Institute for Solid State Physics, University of Tokyo, Roppongi 7-22-1, Minato-ku, Tokyo 106-8666, Japan
^c KYOKUGEN, Osaka University, Toyonaka, Osaka 560-8531, Japan

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The high-pressure phase of (VO)₂P₂O₇ comprises a unique kind of spin-1/2 Heisenberg alternating antiferromagnetic chain, in contrast with the ambient pressure phase containing two crystallographically different chains. Magnetic susceptibility and high-field magnetization data showed the presence of a single spin gap of 23 (magnetization) ~27 (susceptibility) K, not double as observed for the ambient pressure phase. This result shows that the two kinds of chains of the ambient pressure phase have single, different spin gaps.

DOI: 10.12693/APhysPolA.97.205
PACS numbers: 75.10.Jm, 75.40.Cx, 75.50.Ee