Spin transport in the two-dimensional quantum disordered anisotropic Heisenberg model

• Published in: Journal of magnetism and magnetic materials 2014-12, Vol.371, p.89-93
• Main Authors: Lima, L.S., Pires, A.S.T., Costa, B.V.
• Format: Article
• Language: English
• Subjects: Anisotropy; Asymptotic properties; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Diluted model; Dilution; Electronic transport in condensed matter; Exact sciences and technology; General formulation of transport theory; Mathematical models; Percolation; Physics; Spin transport; Theory of electronic transport; scattering mechanisms; Thresholds; Transport; Two dimensional
• ISSN: 0304-8853
• DOI: 10.1016/j.jmmm.2014.07.020

We use the self consistent harmonic approximation together with the Linear Response Theory to study the effect of nonmagnetic disorder on spin transport in the quantum diluted two-dimensional anisotropic Heisenberg model with spin S=1 in a square lattice. The model has a BKT transition at zero dilution. We calculate the regular part of the spin conductivity σreg(ω) and the Drude weight DS(T) as a function of the non-magnetic concentration, x. Our calculations show that the spin conductivity drops abruptly to zero at xcSCHA≈0.5 indicating that the system changes from an ideal spin conductor state to an insulator. This value is far above the site percolation threshold xcsite≈0.41. Although the SCHA fails in determining precisely the percolation threshold, both the spin conductivity and the Drude weight show a quite regular behavior inside 0≤x≤xcSCHA indicating that the transition stays in the same universality class all along the interval. •The site dilution generates a large influence on regular part of the spin conductivity, σreg(ω), and in the Drude weight, D(T).•In a concentration of impurities about x≈0.5, the regular part of the spin conductivity and the Drude weight fall to zero.•In this point we have a change in the state of the system from an ideal spin conductor to a spin insulator.