Spin transport properties of anisotropic Heisenberg antiferromagnet on honeycomb lattice in the presence of magnetic field

Abstract

We have addressed the spin conductivity of a two-dimensional anisotropic antiferromagnet on honeycomb lattice in the presence of a longitudinal magnetic field. A spatial anisotropy in the form of a weak Dzyaloshinskii-Moriya interaction is considered in the model Hamiltonian. Next nearest neighbor exchange coupling has been added to the model Hamiltonian. We have investigated both dynamical and static spin conductivities in terms of the excitation spectrum by means of a hard core bosonic representation. The effects of next-nearest-neighbor coupling and the Dzyaloshinskii-Moriya interaction on the spin transport properties have also been studied via the bosonic model by a Green’s function approach. We have found the temperature dependence of static spin conductivity in the field induced gapped spin-polarized phase for various magnetic field and anisotropy parameters. Furthermore we have studied the magnetic field dependence of the static spin conductivity for various Dzyaloshinskii-Moriya interaction strength and the frequency dependence of the dynamical spin conductivity for various next nearest neighbor coupling constants. We find that the peak in the static spin conductivity moves to higher temperature upon increasing the magnetic field at fixed anisotropy parameter. The static spin conductivity is found to be monotonically decreasing with magnetic field due to increase of the energy gap in the excitation spectrum. Furthermore we have studied the temperature dependence of the spin conductivity for different magnetic field and various next nearest neighbor coupling constants.