Imperfect Many-Body Localization in Exchange-Disordered Isotropic Spin Chains
Abstract
We investigate many-body localization in isotropic Heisenberg spin chains with the local exchange parameters being subject to quenched disorder. Such systems incorporate a nonabelian symmetry in their Hamiltonian by an invariance under global SU(2)-rotations. Nonabelian symmetries are predicted to hinder the emergence of a many-body localized phase even in presence of strong disorder. We report on numerical studies using exact diagonalization for chains of common spin length 1/2 and 1. The averaged consecutive-gap ratios display a transition compatible with a crossover from an ergodic phase at small disorder strength to an incompletely localized phase at stronger disorder. The sample-to-sample variance of the averaged consecutive-gap ratio displays a maximum at the transition and distinguishes the incompletely localized phase from a fully many-body localized phase by its scaling behavior.
Cite
@article{arxiv.2211.04816,
title = {Imperfect Many-Body Localization in Exchange-Disordered Isotropic Spin Chains},
author = {Julian Siegl and John Schliemann},
journal= {arXiv preprint arXiv:2211.04816},
year = {2023}
}