Topological heavy fermions in magnetic field.

The recently introduced topological heavy fermion model (THFM) provides a means for interpreting the low-energy electronic degrees of freedom of the magic angle twisted bilayer graphene as hybridization amidst highly dispersing topological conduction and weakly dispersing localized heavy fermions. In order to understand the Landau quantization of the ensuing electronic spectrum, a generalization of THFM to include the magnetic field B is desired. However the generalization of THFM to magnetic flux seemed elusive because of the failure of the conventional canonical substitution method to account for the correct number of total magnetic subbands within the narrow bands, i.e. its total Chern number. To this end we provide a systematic derivation of the THFM in B and solve the resulting model to obtain the interacting Hofstadter spectra for single particle charged excitations at three different fillings of the moiré unit cell. The presented analytical results offer an intuitive understanding of the nature of the (strongly interacting) Hofstadter bands.