Kinetic magnetism at the interface between Mott and band insulators

We show that the interplay of a high-density two-dimensional electron gas and localized electrons in a neighboring Mott insulator leads to kinetic magnetism unique to the Mott and band insulator interface. Our study is based upon a bilayer Hubbard model at $U=\ensuremath{\infty}$ with a potential difference between the two layers. We combine analytic results with DMRG simulations to show that magnetism, and especially ferromagnetism, is greatly enhanced relative to the proximity of the two subsystems. The results are potentially relevant to recent experiments, suggesting magnetism in $R{\mathrm{TiO}}_{3}/{\mathrm{SrTiO}}_{3}$ heterostructures.