title: Sequence of hole resonances in complex oxide heterostructures.
abstract: Resonant soft x-ray scattering measurements at the O K edge on Sr2CuO4-ν/La2NiO4+δ (SCO/LNO) complex oxide superlattices show resonances for holes in the two constituent layers, in a sequence of energy levels. The observation of well defined resonances, on a superlattice with layers one unit cell thick, indicates that the resonance energy is largely unaffected by atoms outside a cluster extending half a unit cell along the c axis, consistent with calculations for bulk materials. Comparison to measurements on related superlattices confirms that the order of resonances at the O K edge reflects the order of hole ground-state energies in the heterostructure buried layers. For the SCO/LNO superlattices, the measurements show that the ground-state energies remain different in very thin SCO and LNO layers, which is a contributing factor when considering electronic reconstruction at interfaces, in addition to the areal density of ionic charges in the atomic planes. Different hole energy levels in the SCO/LNO superlattice also imply that holes do not spread into SCO from LNO layers.
authors.affiliation: Department of Physics and Astronomy, University of Louisville, Louisville, KY 40292, USA. Frederick Seitz Materials Research Laboratory, University of Illinois, Urbana, IL 61801, USA.
authors.forename: S
authors.initials: S
authors.lastname: Smadici
authors.forename: G
authors.initials: G
authors.lastname: Logvenov
authors.forename: I
authors.initials: I
authors.lastname: Bozovic
authors.forename: P
authors.initials: P
authors.lastname: Abbamonte
mesh_terms: D003300:Copper / Q000737:chemistry*; D007811:Lanthanum / Q000737:chemistry*; D008956:Models, Chemical; D009532:Nickel / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry*; D013324:Strontium / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D010087:Oxides; C103829:lanthanum oxide; D007811:Lanthanum; D003300:Copper; D009532:Nickel; C028007:nickel monoxide; C000520:cuprous oxide; D013324:Strontium