Insulating state of ultrathin epitaxial LaNiO3 thin films detected by hard x-ray photoemission
SCIE
SCOPUS
- Title
- Insulating state of ultrathin epitaxial LaNiO3 thin films detected by hard x-ray photoemission
- Authors
- Gray, AX; Janotti, A; Son, J; LeBeau, JM; Ueda, S; Yamashita, Y; Kobayashi, K; Kaiser, AM; Sutarto, R; Wadati, H; Sawatzky, GA; Van de Walle, CG; Stemmer, S; Fadley, CS
- Date Issued
- 2011-08-03
- Publisher
- Americal Physical Society
- Abstract
- In order to understand the influence of strain and film thickness on the electronic structure of thin films of strongly correlated oxides, we have applied hard x-ray photoemission (HXPS) at 6 keV, soft x-ray photoemission (XPS) at 1.5 keV, and transmission electron microscopy to epitaxial LaNiO3 films deposited on two substrates: LaAlO3 (compressive strain) and (LaAlO3)(0.3)(Sr2AlTaO6)(0.7) (tensile strain). Using inelastic attenuation lengths in LaNiO3 determined from the HXPS data, we have decomposed valence-band spectra into layer-specific contributions. This decomposition is validated by comparing with the results of first-principles calculations using a hybrid functional. The resultant thin-film LaNiO3 densities of states exhibit significant differences in spectral weights for the thinnest LaNiO3 films. A gap opening consistent with a metal-to-insulator transition is observed for the thinnest 2.7 nm LaNiO3 film on an (LaAlO3)(0.3)(Sr2AlTaO6)(0.7) substrate, with a similar gap opening also being observed in complementary soft x-ray photoemission at 1.5 keV for a thinner 1.4 nm film on an LaAlO3 substrate. A metal-to-insulator transition in very thin nm-scale films of LaNiO3 is thus suggested as a general phenomenon.
- URI
- https://oasis.postech.ac.kr/handle/2014.oak/12250
- DOI
- 10.1103/PHYSREVB.84.075104
- ISSN
- 1098-0121
- Article Type
- Article
- Citation
- Physical Review B, vol. 84, no. 7, 2011-08-03
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