The Mott insulator LaTiO_3 in heterostructures with SrTiO_3 is metallic

摘要

It is shown that LaTiO_3 in superlattices with SrTiO_3 is not a Mottinsulator but a strongly correlated metal. The tetragonal lattice geometryimposed by the SrTiO_3 substrate leads to an increase of the Ti 3d t2g bandwidth and a reversal of the t2g crystal field relative to the orthorhombic bulkgeometry. Using dynamical mean field theory based on finite-temperaturemulti-band exact diagonalization we show that, as a result of these effects,local Coulomb interactions are not strong enough to induce a Mott transition intetragonal LaTiO_3. The metalicity of these heterostructures is therefore notan interface property but stems from all LaTiO_3 planes.