Neutron scattering is used to investigate spin correlations in ultra pure single crystals of the S=1 triangular lattice NiGa2S4. Despite a Curie-Weiss temperature of Theta_CW=-80(2) K, static (tau > 1 ns) short range (xi_ab=26(3) \AA) incommensurate order prevails for T>1.5 K. The incommensurate modulation Q_0=(0.155(3),0.155(3),0), Theta_CW, and the spin wave velocity (c=4400 m/s) can be accounted for by antiferromagnetic third-nearest neighbor interactions J_3=2.8(6) meV and ferromagnetic nearest neighbor coupling J_1=-0.35(9) J_3. Inter-plane correlations are limited to nearest neighbors and weakened by an in-plane field. These observations show that the short range ordered glassy phase that has been observed in a number of highly degenerate systems, can persist near the clean limit.
@article{arxiv.1006.3238,
title = {Incommensurate short-range order in the S=1 triangular antiferromagnet NiGa2S4},
author = {C. Stock and S. Jonas and C. Broholm and S. Nakatsuji and Y. Nambu and K. Onuma and Y. Maeno and J. -H. Chung},
journal= {arXiv preprint arXiv:1006.3238},
year = {2015}
}
Comments
4 pages, 4 figures, to be published in Physical Review Letters