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arXiv · 0910.1904

Spin Order and Excitations in Triangular Antiferromagnet La2Ca2MnO7

Wei Bao·Y. X. Wang·Y. Qiu·K. Li·J. H. Lin·J. R. D. Copley·R. W. Erwin·B. S. Dennis·A. P. Ramirez
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Abstract

We report a spin S = 3/2 triangular antiferromagnet with nearest-neighbor coupling J = 0.29 meV in La2Ca2MnO7. A genuinely two-dimensional, three-sublattice order develops below 2.80 K << the Weiss constant (25 K). The spin excitations deviate substantially from linear spin-wave theory, suggesting that magnon breakdown occurs in the material. Such a breakdown has been anticipated in recent theoretical studies, although the excitation spectrum remains to be accounted for.

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Wei Bao, Y. X. Wang, Y. Qiu, K. Li, J. H. Lin, J. R. D. Copley, R. W. Erwin, B. S. Dennis, A. P. Ramirez. 2009-10-10. Spin Order and Excitations in Triangular Antiferromagnet La2Ca2MnO7. https://arxiv.org/abs/0910.1904

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