Driven isotropic Heisenberg spin chain with arbitrary boundary twisting angle: exact results.
We consider an open isotropic Heisenberg quantum spin chain, coupled at the ends to boundary reservoirs polarized in different directions, which sets up a twisting gradient across the chain. Using a matrix product ansatz, we calculate the exact magnetization profiles and magnetization currents in the nonequilibrium steady state of a chain with N sites. The magnetization profiles are harmonic functions with a frequency proportional to the twisting angle θ. The currents of the magnetization components lying in the twisting plane and in the orthogonal direction behave qualitatively differently: In-plane steady-state currents scale as 1/N^{2} for fixed and sufficiently large boundary coupling, and vanish as the coupling increases, while the transversal current increases with the coupling and saturates to 2θ/N.
Dipartimento di Fisica e Astronomia, Università di Firenze, via G. Sansone 1, 50019 Sesto Fiorentino, Italy and Institut für Theoretische Physik, Universität zu Köln, Zülpicher Str. 77, D-50937 Cologne, Germany.
V
V
Popkov
Institut Jean Lamour, dpt. P2M, Groupe de Physique Statistique, Université de Lorraine, CNRS, B.P. 70239, F-54506 Vandoeuvre les Nancy Cedex, France.
D
D
Karevski
Institute of Complex Systems II, Forschungszentrum Jülich, 52428 Jülich, Germany.
G M
GM
Schütz