Incommensurate spin correlations in a spin-1 triangular lattice antiferromagnet

Spin correlations in the triangular lattice antiferromagnet NiGa2S4 were investigated as a function of temperature and magnetic field through neutron scattering. At T=1.5 K the in plane correlations are incommensurate with a wave vector $(\frac{1}{6}-\delta ,\frac{1}{6}-\delta ,0)$ where $\delta =$ 0.00866. The in-plane correlation length is 6.9(8) lattice spacings while inter-plane correlations cannot be detected beyond the second nearest plane. These correlations persist on a time scale that exceeds 0.3 ns. Application of an in-plane magnetic field of 10 Tesla only slightly reduces the inter-plane correlations with no appreciable effect on intra-plane correlations, while heating reduces the frozen moment, the in-plane correlation length, and the correlation time. We shall discuss what can be inferred about the spin Hamiltonian for NiGa2S4 as well as the spin-1 triangular lattice antiferromagnet from these data.