Anisotropy of core-level spectra and the correlation with transport properties of epitaxial lanthanum nickel oxide thin films

Abstract

We studied the electronic structures of (001), (110), and (111) LaNiO3 (LNO) films using XPS. Core-level photoemission spectra analysis reveals that the energy separation ΔE from the satellite to main peaks of Ni 2p1/2 clearly varies in accordance with LNO film orientation. The ΔE in (111) LNO films is 9.71 ± 0.1 eV, larger than the values of 9.39 ± 0.1 and 9.21 ± 0.1 eV in corresponding (001) and (110) films, respectively. This indicates that the Ni 3d–O 2p hopping interaction strength tpd is larger in the (111) LNO films compared with the other two films. The large aforementioned tpd in (111) LNO films also changes the electron states near the Fermi level, which suggests improved electrical conductive properties in (111) LNO films compared with corresponding (110) and (001) films.