Structure and ferromagnetic instability of the oxygen-deficient SrTiO${}_3$ surface

Abstract

SrTiO${}_3$ (STO) is the substrate of choice to grow oxide thin-films and oxide heterojunctions, which can form quasi-two-dimensional electronic phases that exhibit a wealth of phenomena, and, thus, a workhorse in the emerging field of metal-oxide electronics. Hence, it is of great importance to know the exact character of the STO surface itself under various oxygen environments. Using density functional theory within the spin generalized gradient approximation we have investigated the structural, electronic and magnetic properties of the oxygen-deficient STO surface. We find that the surface oxygen vacancies order in periodic arrays giving rise to surface magnetic moments and a quasi two-dimensional electron gas in the occupied Ti 3-d orbitals. The surface confinement, the oxygen-vacancy ordering, and the octahedra distortions give rise to spin-polarized $t_{2g}$ dispersive sub-bands; their energy split near the Brillouin zone center acts as an effective Zeeman term, which, when we turn on a Rashba interaction, produces bands with momentum-spin correlations similar to those recently discovered on oxygen deficient STO surface.

main manuscript 6 two-column pages, five figures. Supplementary materials with seven figures

References in corpus (5)

• Magnetic effects at the interface between nonmagnetic oxides
• Quasiparticle band structure based on a generalized Kohn-Sham scheme
• Persistent Optically Induced Magnetism in Oxygen-Deficient Strontium Titanate
• Ab initio study of the two-dimensional metallic state at the surface of SrTiO3: importance of oxygen vacancies
• Spin-texture induced by oxygen vacancies in Strontium perovskites (001) surfaces: A theoretical comparison between SrTiO3 and SrHfO3

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