Spin and thermal conductivity in a classical disordered spin chain

The transport quantities of a classical spin chain with quenched disorder in antiferromagnetic coupling J(i) are evaluated using a dynamical simulation at finite temperatures T > 0. Since the classical model is nonintegrable, spin and thermal conductivities remain finite even in the pure case. On the other hand, the role of disorder becomes crucial at low T, leading to a vanishing transport due to Anderson localization within the linearized regime. The crossover from the insulator to the conductor appears both for spin and thermal transport at quite low T-star << J. Still the many-body localization regime at T > 0 evidenced by extremely short mean free paths can be strongly enhanced by introducing into the model an additional staggered field.