We consider the effect of a local interatomic repulsion on synthetic
heterostructures where a discrete synthetic dimension is created by
Raman processes on top of SU(N)SU(N)-symmetric
two-dimensional lattice systems. At a filling of one fermion per site,
increasing the interaction strength, the system is driven towards a Mott
state which is adiabatically connected to a band insulator. The chiral
currents associated with the synthetic magnetic field increase all the
way to the Mott transition, where they reach the maximum value, and they
remain finite in the whole insulating state. The transition towards the
Mott-band insulator is associated with the opening of a gap within the
low-energy quasiparticle peak, while a mean-field picture is recovered
deep in the insulating state.