Correlated interface electron gas in infinite-layer nickelate versus cuprate films on SrTiO_{3}(001)

Abstract

Based on first-principles calculations including a Coulomb repulsion term, we identify trends in the electronic reconstruction of ANiO_{2}/SrTiO_{3}(001) (A=Pr, La) and ACuO_{2}/SrTiO_{3}(001) (A=Ca, Sr). Common to all cases is the emergence of a quasi-two-dimensional electron gas (q2DEG) in SrTiO_{3}(001), albeit the higher polarity mismatch at the interface of nickelates versus cuprates to the nonpolar SrTiO_{3}(001) substrate (3+/0 versus 2+/0) results in an enhanced q2DEG carrier density. The simulations reveal a significant dependence of the interfacial Ti 3d_{xy} band bending on the rare-earth-metal ion in the nickelate films, being 20–30% larger for PrNiO_{2} and NdNiO_{2} than for LaNiO_{2}. Contrary to expectations from the formal polarity mismatch, the electrostatic doping in the films is twice as strong in cuprates as in nickelates. We demonstrate that the depletion of the self-doping rare-earth-metal 5d states enhances the similarity of nickelate and cuprate Fermi surfaces in film geometry, reflecting a single hole in the Ni and Cu 3d_{x^{2}−y^{2}} orbitals. Finally, we show that NdNiO_{2} films grown on a polar NdGaO_{3}(001) substrate feature a simultaneous suppression of q2DEG formation as well as Nd 5d self-doping.