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

doi:10.1103/PhysRevB.78.220403

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

IMR - Materials Property Division

Research output: Contribution to journal › Article › peer-review

35 Citations (Scopus)

Abstract

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 T_f 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 T_f, below which NiGa₂S₄ is neither a conventional magnet nor a singlet spin liquid.

Original language	English
Article number	220403
Journal	Physical Review B - Condensed Matter and Materials Physics
Volume	78
Issue number	22
DOIs	https://doi.org/10.1103/PhysRevB.78.220403
Publication status	Published - 2008 Dec 1

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abstract = "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.",

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T1 - Unconventional spin freezing and fluctuations in the frustrated antiferromagnet NiGa2S4

AU - MacLaughlin, D. E.

AU - Nambu, Y.

AU - Nakatsuji, S.

AU - Heffner, R. H.

AU - Shu, Lei

AU - Bernal, O. O.

AU - Ishida, K.

PY - 2008/12/1

Y1 - 2008/12/1

N2 - 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.

AB - 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.

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Unconventional spin freezing and fluctuations in the frustrated antiferromagnet NiGa₂S₄

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