Ba NMR studies of the triangular lattice antiferromagnets Ba$_3$MSb$_2$O$_9$ (M=Co, Ni)

ORAL

Abstract

Ba$_3$MSb$_2$O$_9$, with M=Co, Ni are triangular lattice magnetic systems with near-neighbor antiferromagnetic exchange. For M=Co (S=1/2), the ground state is ordered and there are field-induced changes to the symmetry, whereas for the Ni (S=1) system there is no evidence for a phase transition to a lower-symmetry phase. Here we report on Ba nuclear magnetic resonance (NMR) spectroscopy and spin-lattice relaxation measurements for both systems. For example, the temperature dependence of the relaxation rate is independent of temperature for the Ni-based compound, and is similar to what is observed for the high-symmetry phase of the Co compound. The spin structures for the ordered phases of the Co material are also explored.

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Authors

  • T. Zhou

    • UCLA

  • G. Koutroulakis

    • Los Alamos National Laboratory

  • S.E. Brown

    • UCLA

  • H.D. Zhou

    • University of Tennessee

  • J.G. Cheng

    • Texas Materials Institute, University of Texas at Austin

  • J.S. Brooks

    • National High Magnetic Field Laboratory