Spin superfluidity in the anisotropic XY model in the triangular lattice

•We employ SU(3) Schwinger boson formalism together with the Kubo formula to calculate the spin conductivity.•We find the behavior of AC conductivity σreg(ω)σreg(ω) where the region ΔωΔω where the AC conductivity tends to infinity when ω→0ω→0.•We determine the behavior of the spin transport properties at T=0.

We use the SU(3) Schwinger׳s boson theory to study the spin transport properties in the two-dimensional anisotropic frustrated Heisenberg model in the triangular lattice at T=0. We have investigated the behavior of the spin conductivity for this model which presents an single-ion anisotropy. We study the spin transport in the Bose-Einstein condensation regime where we have that the tz bosons are condensed and the following condition is valid: 〈tz〉=〈tz†〉=t. Our results show a metallic spin transport for ω>0ω>0 and a superfluid spin transport in the limit of DC   conductivity, ω→0ω→0, where σ(ω)σ(ω) tends to infinity in this limit of ω.