Possible spin nematic transition in S=1 dimer compound Cs3V2Cl9

Cs3V2Cl9 is made up with V3+ (S=1) dimer units, which form triangular lattice in basal c-plane. We measured specific heat and magnetic susceptibility of this material using single crystal and found two successive orders at about 4 and 17 K, contrary to the previous report. The former transition at the lower temperature may be a magnetic transition but detail is not known. The latter one is neither a mere structural transition nor a usual magnetic transition. One possibility of the phase transition without usual magnetic order is a spin nematic order in which quadrupole moments, not the magnetic moments, play as an order parameter. It is challenging task to detect the spin nematic phase. We expect thermally fluctuating quadupole moments may induce small magnetic moments which are able to interact muon spins. The aim of this proposal is to investigate the nature of these transitions.