Spin disordered state of the triangular lattice antiferromagnet NiGa$_{2}$S$_{4}$*

We have recently found a spin disordered state in two dimensions in NiGa$_{2}$S$_{4}$, a bulk insulating antiferromagnet on a triangular lattice.Despite strong antiferromagnetic interactions of $\sim $ 80 K, no magnetic long-range order has been observed down to 0.35 K where we instead find nano-scale quasi-static correlation. The spin disordered state appears on cooling through highly degenerate states with an entropy plateau, and exhibits gapless linearly dispersive modes, suggesting coherence beyond the two-spin correlation length. A possible ground state will be discussed.