Predominance of z2-orbitals at the surface of hole- and electron-doped manganites probed by Angle-Resolved Photo-Emission Spectroscopy

The electronic properties of hole- and electron-doped manganites were probed by a combination of x-ray absorption and photoemission spectroscopies. Hole-dopedLa0.7Ba0.3MnO3and electron-doped La0.7Ce0.3MnO3thin films were epitaxially grown on SrTiO3substrates by means of pulsed laser deposition. Ex-situ x-raydiffraction demonstrated the substrate/film epitaxy relation and in-situ low energy electron diffraction provided evidence of high structural order of film surfaces.By combining synchrotron x-ray absorption and x-ray photoemission spectroscopy, evidence of Mn ions into a 2+ state as a result of the Ce4+substitution inthe electron-doped manganites was provided. Angular resolved photo-emission spectroscopy (ARPES) results showed a predominance of z2-orbitals at the surfaceof both hole- and, unexpectedly, electron-doped manganites thus questioning the validity of the commonly accepted scenario describing the electron filling inmanganites’ 3d orbitals in oxide manganites. The precise determination of the electronic and orbital properties of the terminating layers of oxide manganitespaves the way for engineering multi-layered heterostructures thus leading to novel opportunities in the field of quantum electronics.