Spin nematic phase in S=1 triangular antiferromagnets

Spin nematic order is investigated for an S = 1 spin model on a triangular lattice with bilinear-biquadratic interactions. We particularly studied an antiferro nematic order phase with a three-sublattice structure, and magnetic properties are calculated at zero temperature by bosonization. Two types of bosonic excitations are found and we calculated dynamic and static spin correlations. One is a gapless excitation with linear energy dispersion around k similar to 0, and this leads to a finite spin susceptibility at T = 0 and would have a specific heat C(T) similar to T-2 at low temperatures. These behaviors can explain many of the characteristic features of a recently discovered spin liquid state in the triangular magnet, NiGa2S4.