Berlin 2012 – scientific programme

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MA: Fachverband Magnetismus

MA 27: Half-metals and Oxides (jointly with TT)

MA 27.1: Talk

Wednesday, March 28, 2012, 09:30–09:45, EB 202

Scalable Exchange Bias Effect in La_0.66Sr_0.33MnO_3−x/SrTiO₃ thin films — •Daniel Schumacher¹, Alexandra Steffen¹, Jörg Voigt¹, Jürgen Schubert¹, Hailemariam Ambaye², Valeria Lauter², John Freeland³, and Thomas Brückel¹ — ¹Jülich Centre for Neutron Science JCNS and Peter Grünberg Institut PGI, JARA-FIT, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany — ²Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA — ³Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, USA

We present an Exchange Bias (EB) effect of controllable size in La_0.66Sr_0.33MnO_3−x/SrTiO₃ (LSMO/STO) thin films. Samples have been prepared by Pulsed Laser Deposition and High-Pressure Sputter Deposition in oxygen atmosphere at different oxygen pressures. Increased out-of-plane lattice parameters of the LSMO layers and reduced Curie temperatures indicate oxygen deficiencies in the samples grown at lower oxygen pressures. Whereas the growth at high pressures does not lead to an EB effect, we found an increase of the EB and the coercive fields with decreasing oxygen pressure. Polarized Neutron Reflectometry and X-ray Resonant Magnetic Scattering has been performed to analyze the magnetic depth profile. A layer without net magnetization in LSMO at the interface to STO has been detected in an exchange-biased sample, but not in the non-exchanged-biased one. Hence, an antiferromagnetic structure in this region could be present, which causes the EB effect in this system. A possible explanation is given based on the phase diagram of LSMO.