Interaction-enhanced many-body localization in a generalized Aubry-André model

We study the many-body localization (MBL) transition in a generalized Aubry-André model (also known as the GPD model) introduced by Ganeshan, Pixley, and Das Sarma [Phys. Rev. Lett. 114, 146601 (2015)]. In contrast to MBL in other disordered or quasiperiodic models, the interaction seems to unexpectedly enhance MBL in the GPD model in some parameter range. To understand this counterintuitive result, we demonstrate that the highest-energy single-particle band in the GPD model is unstable against weak disorder, which leads to this surprising MBL phenomenon in the interacting model. We develop a mean-field theory description to understand the coupling between extended and localized states, which we validate using extensive exact diagonalization and modified density matrix renormalization group (DMRG-X) numerical results. © 2024 American Physical Society.