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.