Dresden 2011 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 44: Magnetic Half-metals and Oxides I

MA 44.9: Vortrag

Mittwoch, 16. März 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 La_0.7Ca_0.3MnO₃ (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