Spontaneous cationic ordering in chemicalsolution- grown La2CoMnO6 double perovskite thin films

Double perovskite oxides are of interest because of their electric, magnetic, and elastic properties; however, these properties are strongly dependent on the ordered arrangement of cations in the double perovskite structure. Therefore, many efforts have been made to improve the level of cationic ordering to obtain optimal properties while suppressing antisite defect formation. Here, epitaxial double perovskite La2CoMnO6 thin films were grown on top of (001)-STO oriented substrates by a polymer-assisted deposition chemical solution approach. Confirmation of the achievement of full Co/Mn cationic ordering was found by scanning transmission electron microscopy (STEM) measurements; EELS maps indicated the ordered occupancy of B–B′ sites by Co/Mn cations. As a result, optimal magnetic properties (Msat ≈ 6 µB/f.u. and Tc ≈ 230 K) are obtained. We show that the slow growth rates that occur close to thermodynamic equilibrium conditions in chemical solution methods represent an advantageous alternative to physical deposition methods for the preparation of oxide thin films in which complex cationic ordering is involved.We acknowledge financial support from the Spanish Ministry of Economy and Competitiveness through the Severo Ochoa Programme for Centres of Excellence in R&D (SEV-2015-0496), COACHSUPENERGY project (MAT2014-51778-C2-1-R) and MAT2015-71664-R, cofinanced by the European Regional Development Fund. Support from the European Union′s Horizon 2020 Research and Innovation Programme under the Marie Sklodowska-Curie grant agreement no. 645658 (DAFNEOX Project) is also acknowledged. H.W. acknowledges financial support from the China Scholarship Council (CSC). J.G. also acknowledges the Ramon y Cajal program (RYC-2012-11709). The STEM–EELS analysis was sponsored by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division. The authors would like to thank Anna Crespi and Francesc Xavier Campos for assistance with the 3D reciprocal space tomography and reciprocal space map measurements.Peer reviewe