Unconventional spin freezing and fluctuations in the frustrated antiferromagnet NiGa2S4

D. E. MacLaughlin, Y. Nambu, S. Nakatsuji, R. H. Heffner, Lei Shu, O. O. Bernal, K. Ishida

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35 Citations (Scopus)


Muon spin rotation (μSR) experiments reveal unconventional spin freezing and dynamics in the two-dimensional (2D) triangular lattice antiferromagnet NiGa2S4. Long-lived disordered Ni-spin freezing (correlation time ≳10-6 s at 2 K) sets in below T f=8.5±0.5 K with a mean-field-like temperature dependence. The observed exponential temperature dependence of the muon spin relaxation above Tf is strong evidence for 2D critical spin fluctuations. Slow Ni-spin fluctuations coexist with quasistatic magnetism at low temperatures but are rapidly suppressed for fields ≳10 mT, in marked contrast with the field-independent specific heat. The μSR and bulk susceptibility data indicate a well-defined 2D phase transition at Tf, below which NiGa2S4 is neither a conventional magnet nor a singlet spin liquid.

Original languageEnglish
Article number220403
JournalPhysical Review B - Condensed Matter and Materials Physics
Issue number22
Publication statusPublished - 2008 Dec 1


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