title: Polarity compensation in ultra-thin films of complex oxides: the case of a perovskite nickelate.
abstract: We address the fundamental issue of growth of perovskite ultra-thin films under the condition of a strong polar mismatch at the heterointerface exemplified by the growth of a correlated metal LaNiO3 on the band insulator SrTiO3 along the pseudo cubic [111] direction. While in general the metallic LaNiO3 film can effectively screen this polarity mismatch, we establish that in the ultra-thin limit, films are insulating in nature and require additional chemical and structural reconstruction to compensate for such mismatch. A combination of in-situ reflection high-energy electron diffraction recorded during the growth, X-ray diffraction, and synchrotron based resonant X-ray spectroscopy reveal the formation of a chemical phase La2Ni2O5 (Ni(2+)) for a few unit-cell thick films. First-principles layer-resolved calculations of the potential energy across the nominal LaNiO3/SrTiO3 interface confirm that the oxygen vacancies can efficiently reduce the electric field at the interface.
authors.affiliation: Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, USA.
authors.forename: S
authors.initials: S
authors.lastname: Middey
authors.affiliation: Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, USA.
authors.forename: P
authors.initials: P
authors.lastname: Rivero
authors.affiliation: Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, USA.
authors.forename: D
authors.initials: D
authors.lastname: Meyers
authors.affiliation: Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, USA.
authors.forename: M
authors.initials: M
authors.lastname: Kareev
authors.affiliation: Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, USA.
authors.forename: X
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Cao
authors.affiliation: Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA.
authors.forename: J W
authors.initials: JW
authors.lastname: Freeland
authors.affiliation: Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, USA.
authors.forename: S
authors.initials: S
authors.lastname: Barraza-Lopez
authors.affiliation: Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, USA.
authors.forename: J
authors.initials: J
authors.lastname: Chakhalian