Diffusive and subdiffusive spin transport in the ergodic phase of a many-body localizable system

• Published in: arXiv.org
• Main Authors: Znidaric, Marko, Scardicchio, Antonello, Varma, Vipin Kerala
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 25.07.2016
• Subjects: Anisotropy; Chains; Crossovers; Ergodic processes; High temperature; Physics - Disordered Systems and Neural Networks; Physics - Strongly Correlated Electrons; Size effects
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1604.08567

We study high temperature spin transport in a disordered Heisenberg chain in the ergodic regime. By employing a density matrix renormalization group technique for the study of the stationary states of the boundary-driven Lindblad equation we are able to study extremely large systems (400 spins). We find both a diffusive and a subdiffusive phase depending on the strength of the disorder and on the anisotropy parameter of the Heisenberg chain. Studying finite-size effects we show numerically and theoretically that a very large crossover length exists that controls the passage of a clean-system dominated dynamics to one observed in the thermodynamic limit. Such a large length scale, being larger than the sizes studied before, explains previous conflicting results. We also predict spatial profiles of magnetization in steady states of generic nondiffusive systems.