  In the fermionic sector of top-down approaches to holographic systems, one
generically finds that the fermions are coupled to gravity and gauge fields in
a variety of ways, beyond minimal coupling. In this paper, we take one such
interaction -- a Pauli, or dipole, interaction -- and study its effects on
fermion correlators. We find that this interaction modifies the fermion
spectral density in a remarkable way. As we change the strength of the
interaction, we find that spectral weight is transferred between bands, and
beyond a critical value, a hard gap emerges in the fermion density of states. A
possible interpretation of this bulk interaction then is that it drives the
dynamical formation of a (Mott) gap, in the absence of continuous symmetry
breaking.
