Nano-faceted stabilization of polar-oxide thin films: The case of MgO(111) and NiO(111) surfaces

TY - JOUR

T1 - Nano-faceted stabilization of polar-oxide thin films

T2 - The case of MgO(111) and NiO(111) surfaces

AU - Kerrigan, A.

AU - Pande, K.

AU - Pingstone, D.

AU - Cavill, S. A.

AU - Gajdardziska-Josifovska, M.

AU - McKenna, K. P.

AU - Weinert, M.

AU - Lazarov, V. K.

N1 - Funding Information: This work was supported by the Engineering and Physical Sciences Research Council ( EP/N509802/1 ). Some of this project was undertaken on the Viking Cluster, which is a high performance compute facility provided by the University of York. We are grateful for computational support from the University of York High Performance Computing service, Viking and the Research Computing team. Funding Information: This work was supported by the Engineering and Physical Sciences Research Council (EP/N509802/1). Some of this project was undertaken on the Viking Cluster, which is a high performance compute facility provided by the University of York. We are grateful for computational support from the University of York High Performance Computing service, Viking and the Research Computing team. Publisher Copyright: © 2022 The Authors

PY - 2022/9/15

Y1 - 2022/9/15

N2 - Molecular beam epitaxy growth of polar MgO(111) and NiO(111) films demonstrates that surface stabilization of the films is achieved via the formation of neutral nano-faceted surfaces. First-principles modeling of the growth of polar MgO(111) films reveals that the growth does not proceed layer-by-layer. Instead, the Mg or O layers grow up to a critical sub-monolayer coverage, beyond which the growth of the next layer becomes energetically favorable. This non-layer-by-layer growth is accompanied by complex relaxations of atoms both at the surface and in the sub-surface, and leads to the experimentally observed surface nano-faceting of MgO and NiO (111) films through formation of neutral nano-pyramids terminated by {100} facets. These facets are limited in size by an asymptotical surface energy relation to their height; with the reconstruction being much more stable than previously reported surface terminations across a wide range of growth conditions. The termination offers access to lower coordinated atoms at the intersection of the neutral {100} planes whilst also increasing the surface area of the film. The unique electronic structures of these surfaces can be utilized in catalysis, as well for forming unique heterostructures for electronic and spintronic applications.

AB - Molecular beam epitaxy growth of polar MgO(111) and NiO(111) films demonstrates that surface stabilization of the films is achieved via the formation of neutral nano-faceted surfaces. First-principles modeling of the growth of polar MgO(111) films reveals that the growth does not proceed layer-by-layer. Instead, the Mg or O layers grow up to a critical sub-monolayer coverage, beyond which the growth of the next layer becomes energetically favorable. This non-layer-by-layer growth is accompanied by complex relaxations of atoms both at the surface and in the sub-surface, and leads to the experimentally observed surface nano-faceting of MgO and NiO (111) films through formation of neutral nano-pyramids terminated by {100} facets. These facets are limited in size by an asymptotical surface energy relation to their height; with the reconstruction being much more stable than previously reported surface terminations across a wide range of growth conditions. The termination offers access to lower coordinated atoms at the intersection of the neutral {100} planes whilst also increasing the surface area of the film. The unique electronic structures of these surfaces can be utilized in catalysis, as well for forming unique heterostructures for electronic and spintronic applications.

KW - Electron microscopy

KW - First-principles

KW - Nano-faceting

KW - Polar-oxide

KW - Thin-film

UR - http://www.scopus.com/inward/record.url?scp=85130175881&partnerID=8YFLogxK

U2 - 10.1016/j.apsusc.2022.153490

DO - 10.1016/j.apsusc.2022.153490

M3 - Article

AN - SCOPUS:85130175881

SN - 0169-4332

VL - 596

JO - APPLIED SURFACE SCIENCE

JF - APPLIED SURFACE SCIENCE

M1 - 153490

ER -