Tuning the orbital ordering in La 0.7 Sr 0.3 MnO 3 thin films in all-oxide hybrids

This work presents a systematic characterization including x-ray diffractometry,SQUID magnetometry and x-ray absorption spectroscopy on all-oxide ferromagnetic/ferroelectricheterosystem BaTiO3/La0.7Sr0.3MnO3/SrTiO3(001) fabricated by pulsed-laser deposition. Thekey aspect of this study is to provide accurate information about differences in electronic andstructural properties in LSMO thin films as a function of the oxygen pressure during BTO growth.X-ray absorption spectroscopy experiments at the Mn L3,2 edge have revealed the conservation ofMn3+/Mn4+ mixed valency configuration of the LSMO films near the interface while tuning theoxygen pressure of overlayer BTO growth. The existing Mn3+ ions favor an in-plane eg orbitalordering, reducing the in-plane strain and promoting room temperature ferromagntism in theLSMO film. Furthermore, diffraction experiments showed that the out-of plane lattice parameterof BTO reduces with increasing oxygen pressure consistent with the x-ray linear dichrosim at Tiedge showing less tetragonal symmetry, although the chemical environment of the Ti ions was notchanged notably. We demonstrated a way to control magnetic properties and orbital ordering inLSMO thin films while optimizing the ferroelectric properties of BTO overlayer films, which arepromising results in terms of magnetoelectric applications using functional heterosystems