We study the one-dimensional Hubbard model for two-component fermions with infinitely strong on-site repulsion ($t-0$ model) in the presence of disorder. Our analytical treatment demonstrates that the type of disorder drastically changes the nature of the emerging phases. The case of spin-independent disorder can be treated as a single-particle problem with Anderson localization. On the contrary, recent numerical findings show that spin-dependent disorder, which can be realized as a random magnetic field, leads to the many-body localization-delocalization transition. We find an explicit analytic expression for the matrix elements of the random magnetic field between the eigenstates of the $t-0$ model with potential disorder on a finite lattice. Analysis of the matrix elements supports the existence of the many-body localization-delocalization transition in this system and provides an extended physical picture of the random magnetic field.

• Received 25 October 2022
• Revised 23 April 2023
• Accepted 5 May 2023

DOI:https://doi.org/10.1103/PhysRevB.107.184202