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Chalcogenides with the GaM₄S₈ structure are hetero- cubane like [M₄X₄]ⁿ⁺ cubes (M = Mo, Re,V, Nb, Ta; X = S, Se, Te) and [AX₄]^n- tetrahedra (A= Ga, Ge), these adopt the NaCl structure[1,2]. GaV₄S₈ is a known Mott insulator because of the long inter-cluster distances approximately 4 Å apart [1]. GaV₄S₈ (GaVS) is a magnetic semiconductor with a Neel-type skyrmion phase displaying multiferroic properties [3]. Magnetic susceptibility measurements showed structural transition at T_JT of 42 K followed by a ferromagnetic order at 12 K [4] and 12.7 K [5]. Temperature-dependent infrared and Raman measurements identified phonon modes and Jahn-Teller distortions [6]. For detailed information on the various exchange interactions in GaV₄S₈, we performed magneto-Raman measurements at magnetic fields up to 20 T and temperatures down to 5 K.

References:
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[2] V. Malik et. al. EPL, 101, 67008 (2013)
[3] I. Kézsmárki et. al. Nat. Matter. 14, 1116 (2015)
[4] C.S. Yadav et al. Phys. Rev. B: Condens. Matter. 403, 1474 (2008)
[5] S. Reschke et. al. PHY. REV. B 96, 144302 (2017)
[6] J. Hlinka et al. Phys. Rev. B. 94, 060104 (2016)