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MA: Fachverband Magnetismus
MA 44: Magnetic Half-metals and Oxides I
MA 44.9: Talk
Wednesday, March 16, 2011, 19:00–19:15, HSZ 401
YBCO/LCMO bilayers: Interface coupling and electric transport properties — •Christoph Raisch1, Robert Werner2, Adele Ruosi3, Bruce Davidson4, Mathias Glaser1, Reinhold Kleiner2, Dieter Koelle2, and Thomas Chassé1 — 1Institut für Physikalische Chemie, Uni Tübingen, Germany — 2Physikalisches Institut, Experimentalphysik II, Uni Tübingen, Germany — 3CNR-SPIN and Dept. of Physics, University of Naples Federico II, Italy — 4CNR-IOM TASC National Laboratory, Basovizza, Trieste, Italy
We studied bilayers of La0.7Ca0.3MnO3 (LCMO) and YBa2Cu3O7 (YBCO) [1]. We investigated the unoccupied electronic structure by X-ray Absorption Spectroscopy (XAS), the magnetization of Mn and Cu species by X-ray Magnetic Circular Dichroism (XMCD) and the orbital occupation of the transition metal atoms by Linear Dichroism (LD) measurements. While we could reproduce earlier XMCD data and their temperature dependence [2], we could not find any evidence for charge transfer across the interface or orbital reconstruction on copper [3]. The results of our transport measurements indicate a suppression of the superconducting transition temperature only below a YBCO film thickness of 5nm. This hints to an electronically less transparent interface, probably due to a stronger hybridization between Mn and Cu via O at the interface. From the analysis of our data, we conclude that covalent bonding and the resulting orbital reconstruction are not necessary for the spin canting of Cu moments in proximity to Mn spins. [1] Werner, PRB, accepted, [2] Chakhalian, Nature Physics 2, [3] Chakhalian, Science 318