Figure 1

Sample preparation and structural characterization.
(a) XRD θ−2θ scans around the (002) peaks of 84 u.c. NNO films on the two different substrates. The ‘S’ and ‘F’ denote the substrates and NNO films, respectively. Clear Kiessig fringes indicate the high quality of the films. (b) c-axis lattice parameters as functions of NNO film thickness. The insets show the lattice distortion under different strains, respectively. Topography images of 20 u.c. NNO films on (c) STO and (d) LAO substrates, respectively.