Abstract
We study spin transport in a Hubbard chain with a strong, random, on-site potential and with spin-dependent hopping integrals . For the SU(2) symmetric case , such a model exhibits only partial many-body localization with localized charge and (delocalized) subdiffusive spin excitations. Here, we demonstrate that breaking the SU(2) symmetry by even weak spin asymmetry, , localizes spins and restores full many-body localization. To this end we derive an effective spin model, where the spin subdiffusion is shown to be destroyed by arbitrarily weak . Instability of the spin subdiffusion originates from an interplay between random effective fields and singularly distributed random exchange interactions.
- Received 29 January 2019
- Revised 8 March 2019
DOI:https://doi.org/10.1103/PhysRevB.99.121110
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