Stabilizing and detecting electron fractionalization in the Hofstadter-Hubbard model

Motivated by the recent progress in correlated Chern insulator physics in moiré systems, we investigate the half-filled triangular-lattice Hofstadter--Hubbard model and its electron fractionalization. Among various competing non-magnetic states, increasing the orbital flux stabilizes and broadens the U(1) 2 chiral spin liquid phase in the Mott regime. In this exotic regime, the electron is fractionalized into gapped spinons and gapped chargons, whose effective bands are linked to the orbital flux. The convolution of the narrow spinon bands with the gapped chargon excitations produces rich and discernible structures in the electron spectral function and the density of states. These results not only identify the orbital flux as a control parameter for the detailed patterns of electron fractionalization and the nature of the Mott transition, but also provide the key spectral characteristics for the angle-resolved photoemission and scanning tunneling studies of the relevant systems, linking the free-particle band topology to intrinsic topological order in the correlated regime.