  Using density functional theory calculations, ultrathin films of SrVO3(d1)
and SrCrO3(d2) on SrTiO3 substrates have been studied as possible
multiferroics. Although both are metallic in the bulk limit, they are found to
be insulating as a result of orbital ordering driven by lattice distortions at
the ultrathin limit. While the distortions in SrVO3 have a first-order
Jahn-Teller origin, those in SrCrO3 are ferroelectric in nature. This route to
ferroelectricity (FE) results in polarizations comparable with conventional
ferroelectrics.
