Surface atomic structure of epitaxialLaNiO3thin films studied byin situLEED-I(V)

Abstract

We report in situ low-energy electron diffraction intensity versus voltage [LEED-$I$($V$)] studies of the surface atomic structure of epitaxially grown ${(001)}_{\text{pc}}$-oriented $(\text{pc}=\text{pseudocubic})$ thin films of the correlated $3d$ transition-metal oxide ${\mathrm{LaNiO}}_{3}$. Our analysis indicates the presence of large out-of-plane bucklings of the topmost LaO layers but only minor bucklings of the topmost ${\mathrm{NiO}}_{2}$ layers, in close agreement with earlier surface x-ray diffraction data. In view of materials design approaches that have suggested using atomic-scale polar structural distortions to produce designer electronic structures in artificial nickelate heterostructures, we propose that the broken inversion symmetry inherent to the surface of rare-earth nickelate thin films offers a similar opportunity to study the coupling between atomic structure and electronic properties in this family of materials.