Negative differential conductivity in far-from-equilibrium quantum spin chains

TL;DR

This paper demonstrates that far-from-equilibrium quantum spin chains exhibit negative differential conductivity due to edge ferromagnetic domains, with results explained by magnon localization and stability against integrability breaking.

Contribution

It reveals the emergence of negative differential conductivity in anisotropic Heisenberg spin chains driven far from equilibrium, highlighting the role of edge domain formation and magnon localization.

Findings

Edge ferromagnetic domains suppress spin transport.

Negative differential conductivity occurs with increased driving.

Results are stable against breaking of integrability.

Abstract

We show that, when a finite anisotropic Heisenberg spin-1/2 chain in the gapped regime is driven far from equilibrium, oppositely polarized ferromagnetic domains build up at the edges of the chain, thus suppressing quantum spin transport. As a consequence, a negative differential conductivity regime arises, where increasing the driving decreases the current. The above results are explained in terms of magnon localization and are shown to be structurally stable against breaking of integrability.