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arXiv · 2005.06073

Impact of the lattice on magnetic properties and possible spin nematicity in the S=1 triangular antiferromagnet NiGa$_2$S$_4$

Michael E. Valentine·Tomoya Higo·Yusuke Nambu·Dipanjan Chaudhuri·Jiajia Wen·Collin Broholm·Satoru Nakatsuji·Natalia Drichko
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Abstract

NiGa$_2$S$_4$ is a triangular lattice S=1 system with strong two-dimensionality of the lattice, actively discussed as a candidate to host spin-nematic order brought about by strong quadrupole coupling. Using Raman scattering spectroscopy we identify a phonon of E$_g$ symmetry which can modulate magnetic exchange $J_1$ and produce quadrupole coupling. Additionally, our Raman scattering results demonstrate a loss of local inversion symmetry on cooling, which we associate with sulfur vacancies. This will lead to disordered Dzyaloshinskii-Moriya interactions, which can prevent long range magnetic order. Using magnetic Raman scattering response we identify 160~K as a temperature of an upturn of magnetic correlations. The temperature below 160~K, but above 50~K where antiferromagnetic magnetic start to increase, is a candidate for spin-nematic regime.

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Michael E. Valentine, Tomoya Higo, Yusuke Nambu, Dipanjan Chaudhuri, Jiajia Wen, Collin Broholm, Satoru Nakatsuji, Natalia Drichko. 2020-05-12. Impact of the lattice on magnetic properties and possible spin nematicity in the S=1 triangular antiferromagnet NiGa$_2$S$_4$. https://doi.org/10.1103/physrevlett.125.197201

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