Fundamental difference in the electronic reconstruction of infinite-layer versus perovskite neodymium nickelate films on SrTiO3(001)

Abstract

Motivated by recent reports of superconductivity in Sr-doped NdNiO2 films on SrTiO3(001) [Nature (London) 572, 624 (2019)], we explore the role of the polar interface on the structural and electronic properties of NdNiOn/SrTiO3(001) (n=2,3) by performing first-principles calculations including a Coulomb repulsion term. For infinite-layer nickelate films (n=2), electronic reconstruction drives the surprising emergence of a two-dimensional electron gas (2DEG) at the interface involving a strong occupation of the Ti 3d states. This effect is more pronounced than in LaAlO3/SrTiO3(001) and accompanied by a substantial reconstruction of the Fermi surface: a depletion of the self-doping Nd 5d states and an enhanced Ni eg orbital polarization reaching up to 35% at the surface, reflecting a single hole in the 3dx2−y2 states, i.e., cupratelike behavior. In contrast, no 2DEG forms for perovskite films (n=3) or if a single perovskite layer persists at the interface. We show that the topotactic reaction from the perovskite to the infinite-layer phase is confined to the nickelate film, whereas the SrTiO3 substrate remains intact.

Source-reported materials — not catalogue approval

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