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

¹  CNISM, CNR-INFM, and Center for Nonlinear and Complex Systems, Università degli Studi dell'Insubria Via Valleggio 11, 22100 Como, Italy, EU
²  Istituto Nazionale di Fisica Nucleare, Sezione di Milano - Via Celoria 16, 20133 Milano, Italy, EU
³  Centre for Quantum Technologies, National University of Singapore - Singapore 117543
⁴  Physics Department, Faculty of Mathematics and Physics, University of Ljubljana - Ljubljana, Slovenia, EU
⁵  International School for Advanced Studies (SISSA) - Via Beirut 2-4, I-34014 Trieste, Italy, EU

Corresponding author: drossini@sissa.it

Received: 31 October 2008
Accepted: 7 January 2009

Abstract

We show that, when a finite anisotropic Heisenberg spin- 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.