Berlin 2015 – scientific programme

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KR: Fachgruppe Kristallographie

KR 5: Multiferroics II (DF jointly with DS, KR, MA,TT)

KR 5.6: Talk

Wednesday, March 18, 2015, 16:30–16:45, EB 107

Origin of superstructures in (double) perovskite thin films — •Vikas Shabadi, Marton Major, Philipp Komissinskiy, Aldin Radetinac, Mehran Vafaee, Wolfgang Donner, and Lambert Alff — Institute of Materials Science, Technische Universität Darmstadt, Alarich-Weiss-Strasse 2, 64287 Darmstadt, Germany

We have investigated the origin of superstructure peaks as observed by X-ray diffraction of multiferroic Bi(Fe_0.5Cr_0.5)O₃ thin films grown by pulsed laser deposition on single crystal SrTiO₃ substrates. The photon energy dependence of the contrast between the atomic scattering factors of Fe and Cr is used to rule out a chemically ordered double perovskite Bi₂FeCrO₆ (BFCO). Structural calculations suggest that the experimentally observed superstructure occurs due to unequal cation displacements along the pseudo-cubic [111] direction that mimic the unit cell of the chemically ordered compound [1]. This result helps to clarify discrepancies in the correlations of structural and magnetic order reported for Bi₂FeCrO₆. The observation of a superstructure in itself is not a sufficient proof of chemical order in double perovskites.

[1] V. Shabadi, M. Major, P. Komissinskiy, M. Vafaee, A. Radetinac, M. Baghaie Yazdi, W. Donner, and L. Alff, J. Appl. Phys. 116, 114901 (2014).