Spin Transport Properties of Alternating Heisenberg Chain in the Presence of Longitudinal Magnetic Field

Abstract

We have addressed the spin conductivity and spin Drude weight of one-dimensional spin-1/2 isotropic alternating Heisenberg chain in the finite magnetic field. We have investigated the behavior of transport properties by means of excitation spectrum in terms of a hard core bosonic representation. The effect of dimerization parameter on the spin transport properties has also been studied via the bosonic model by Green’s function approach. We have found the temperature dependence of the static spin conductivity and spin Drude weight in the gapped field induced spin-polarized phase for various amounts of magnetic field and dimerization parameters. Furthermore, we have studied the magnetic field dependence of spin Drude weight for various dimerization parameters. The static spin conductivity is found to be monotonically increasing with temperature at low temperatures due to increase of excitation rate of bosons from ground state to first excited state. Upon more increasing temperature, static spin conductivity reaches a constant value and uniformly behaves at higher temperatures. The effects of both magnetic field and dimerization parameter on the temperature behavior of static spin conductivity are investigated. We also find the peak in the dynamical spin conductivity factor moves to higher frequency upon increasing the dimerization parameter for fixed magnetic field.