1210.4555 (V. Popkov)

Alternation of sign of magnetization current in driven XXZ chains with
twisted XY boundary gradients    [PDF]

V. Popkov

A perturbative approach for a Lindblad Master equation (LME) is developed. As an example, an XXZ spin 1/2 chain is investigated driven out of equilibrium by coupling with boundary reservoirs targeting different spin orientations in XY plane. Exact nonequilibrium steady state for strong couplings is determined by solving secular conditions which guarantee self-consistency of the perturbative expansion. A number of unusual properties is revealed including (i) decoupling of energy and magnetization currents in the steady state (ii) sign alteration of the magnetization current with a system size (iii) nontrivial dependence of the magnetization current on a spin chain anisotropy $\Delta$ in the critical region. Steady magnetization current sign change with system size is a consequence of different LME symmetries for spin chains with odd and even sizes. This phenomenon is robust and does not depend on integrability

View original: http://arxiv.org/abs/1210.4555