Strain effects on the spin polarized electron gas in ABO₃/SrTiO₃ (A = Pr, Nd and B = Al, Ga) heterostructures

The spin polarized two dimensional electron gas in the correlated ABO₃/SrTiO₃ (A = Pr, Nd and B = Al, Ga) heterostructures is investigated by ab-initio calculations using density functional theory. Structural relaxation shows a strong buckling at and near the TiO₂ terminated n-type interface (IFs) due to significant TiO₆ octahedral distortions. We find in all cases, metallic states in a very narrow region of the SrTiO₃, in agreement with experimental results. We demonstrate that the interface magnetism strongly reacts to the magnitude of the lattice strain. The orbital occupations and, hence, the charge carrier density change systematically as a function of the lattice mismatch between the component materials.