Direct observation of infinite NiO2 planes in LaNiO2 films

Abstract Epitaxial thin films of LaNiO 2 , which is an oxygen-deficient perovskite with “infinite layers” of Ni 1+ O 2 , were prepared by a low-temperature reduction of LaNiO 3 single-crystal films on NdGaO 3 substrates. We report the high-angle annular dark-field and bright-field scanning transmission electron microscopy observations of infinite NiO 2 planes of c -axis-oriented LaNiO 2 epitaxial thin films with a layer stacking sequence of NiO 2 /La/NiO 2 . Resistivity measurements on the films show T 2 dependence between 400 and 150 K and a negative Hall coefficient.