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Unconventional spin fluctuations in the hexagonal antiferromagnet YMnO$_3$

T. J. Sato·S. -H. Lee·T. Katsufuji·M. Masaki·S. Park·J. R. D. Copley·H. Takagi
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Abstract

We used inelastic neutron scattering to show that well below its Néel temperature, $T_{\rm N}$, the two-dimensional (2D) XY nearly-triangular antiferromagnet YMnO$_{3}$ has a prominent {\it central peak} associated with 2D antiferromagnetic fluctuations with a characteristic life time of 0.55(5) ps, coexisting with the conventional long-lived spin-waves. Existence of the two time scales suggests competition between the Néel phase favored by weak interplane interactions, and the Kosterlitz-Thouless phase intrinsic to the 2D XY spin system.

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T. J. Sato, S. -H. Lee, T. Katsufuji, M. Masaki, S. Park, J. R. D. Copley, H. Takagi. 2003-04-18. Unconventional spin fluctuations in the hexagonal antiferromagnet YMnO$_3$. https://doi.org/10.1103/physrevb.68.014432

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