Spin liquid phases of large-spin Mott insulating ultracold bosons

Mott insulating ultracold gases possess a unique whole-atom exchange interaction which enables large quantum fluctuations between the Zeeman sublevels of each atom. By strengthening this interaction-either through the use of large-spin atoms or by tuning the particle-particle interactions via optical Feshbach resonance-one may enhance fluctuations and facilitate the appearance of the long-sought-after quantum spin liquid phase-all in the highly tunable environment of cold atoms. To illustrate the relationship between the spin magnitude, interaction strength, and resulting magnetic phases, we present and solve a mean-field theory for bosons optically confined to the one-particle-per-site Mott state, using both analytic and numerical methods. We find on square and triangular lattices for bosons of hyperfine spin f > 2 that making the repulsive s-wave scattering length through the singlet channel small-relative to the higher-order scattering channels-accesses a short-range resonating valence bond (s-RVB) spin liquid phase.