Zusammenfassung
Motivated by recent experiments on material Ba3NiSb2O9, we propose two novel
spin liquid phases (A and B) for spin-1 systems on a triangular lattice. At the
mean field level, both spin liquid phases have gapless fermionic spinon
excitations with quadratic band touching, thus in both phases the spin
susceptibility and C_v/T saturate to a constant at zero temperature, which are
consistent with the experimental results on Ba3NiSb2O9. On the lattice scale,
these spin liquid phases have Sp(4) ~ SO(5) gauge fluctuation; while in the
long wavelength limit this Sp(4) gauge symmetry is broken down to U(1)xZ_2 in
type A spin liquid phase, and broken down to Z_4 in type B phase. We also
demonstrate that the $A$ phase is the parent state of the ferro-quadrupole
state, nematic state, and the noncollinear spin density wave state.
Nutzer