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arXiv · 0805.3749

Unique Phase Transition on Spin-2 Triangular Lattice of Ag2MnO2

Hiroyuki Yoshida·Sascha Ahlert·Martin Jansen·Yoshihiko Okamoto·Jun-Ichi Yamaura·Zenji Hiroi
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Abstract

Ag2MnO2 is studied as a possible candidate compound for an antiferromagnetic XY spin model on a triangular lattice. In spite of the large Curie-Weiss temperature of -430 K found in magnetic susceptibi-lity, Mn3+ spins with S = 2 do not undergo a conventional long-range order down to 2 K probably owing to the geometrical frustration and two dimensionality in the system. Instead, a unique phase transition is found at 80 K, where specific heat exhibits a clear sign of a second-order phase transition, while magnetic susceptibility changes smoothly without a distinct anomaly. We think that this transition is related to the chirality degree of freedom associated with a short-range order, which has been expected for the classical XY spin model on a triangular lattice. On further cooling, spin-glass-like behavior is observed below 22 K, possibly corresponding to a quasi-long-range order.

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Hiroyuki Yoshida, Sascha Ahlert, Martin Jansen, Yoshihiko Okamoto, Jun-Ichi Yamaura, Zenji Hiroi. 2008-05-24. Unique Phase Transition on Spin-2 Triangular Lattice of Ag2MnO2. https://doi.org/10.1143/jpsj.77.074719

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