Influence of quantum phase transition on spin conductivity in the anisotropic three-dimensional ferromagnetic model

We use the SU(3) Schwinger boson formalism to study the spin transport in the three-dimensional S=1 Heisenberg ferromagnet in the cubic lattice with an easy plane crystal field, considering first-, second- and third-neighbor interactions. We have got one single peak for the spin conductivity for this system at ω=ωk and a variation of the height of the peak with the parameters Dc and η, and hence an influence of the quantum phase transition, between the disordered paramagnetic phase and the ordered ones, on the spin conductivity of this system. We have considered the exchange interaction J1 as ferromagnetic and the interactions J2 and J3 as antiferromagnetic.