Figure 1: STEM/EELS of LSCO/LSMO interfaces with two different atomic stacking sequences.
HAADF images of (a) type A and (b) type B interface (left) and the corresponding schematic arrangement of atoms and of Cu and Mn 3dz2 orbitals (right). (c) Layer-resolved Mn-L2,3 and Cu L2,3 EELS spectra; each curve is the average of five spectra acquired sequentially along a lattice plane parallel to the interface (5 pixels of a spectrum image of the near-interface region). A constant background has been subtracted and the spectra have been normalised to the L2 edge. The Cu spectra have been smoothed by adjacent averaging. (d) Valence of Mn as function of the atomic layer determined from the O-K spectra of LSMO layer using the method of ref. 18 which is based on the energy separation ΔE between the main peak and the pre-peak as depicted in Supplementary Fig. 3 (the red line is a guide for the eye). The error bars are evaluated from the uncertainty in the determination of the relative peak position and from the inaccuracy of the phenomenological relation between ΔE and the actual valence. The error bars are also comparable with the standard deviation of the Mn valence as determined by a statistical analysis over several atomic columns.
