Nanoscale analysis of a SrTiO3/La2/3Sr1/3MnO3 interface -: art. no. 014417

The aim of the present work is an atomic scale characterization of the SrTiO3/La2/3Sr1/3MnO3 interface involved in Co/SrTiO3/La2/3Sr1/3MnO3 tunnel junctions. Our high-resolution transmission electron microscopy experiments show the quality of the pseudo-morphic growth of La2/3Sr1/3MnO3 (LSMO) and SrTiO3 (STO), but do not allow us to determine the termination of LSMO. On the other hand, we have carried out an energy-loss near-edge structure study of the Mn-2p and O-1s edges. The main result is that the valence of Mn keeps its intrinsic value of the bulk material till the last MnO2 layers at the interface, which is consistent with the observation of magnetoresistance up to practically the Curie temperature of bulk LSMO in our junctions. These results suggest a La2/3Sr1/3O termination of LSMO.