The preparation of cation-ordered thin films of correlated oxides is of great interest for both fundamental and applied research. The scientific long-term vision is strongly motivated by the perspective of studying electronic correlations in condensed matter without the presence of chemical or quenched disorder. A promising material platform provides double perovskite A₂BB’O₆ bulk samples with different types of B/B’ ordering. However, the growth of A- and/or B-site-ordered correlated oxide thin films is known to be a challenging task. In this review, we evaluate the growth of double perovskite A₂BB’O₆ thin films by means of well-elaborated physical vacuum deposition techniques, such as pulsed laser deposition (PLD) and sputtering and compare them with a close-to-equilibrium growth with the metalorganic aerosol deposition (MAD) technique. The latter was further developed to grow an emergent interfacial double perovskite phase in LaNiO₃/LaMnO₃ superlattices, and finally, by way of a layer-by-layer route. The growth of La₂CoMnO₆ films on SrTiO₃(111) substrates by sequential deposition of single perovskite layers of LaCoO₃/LaMnO₃/LaCoO₃/… was demonstrated and the film properties were compared to those obtained within the state-of-the art growth mode.

We report ${\left[{\left({\mathrm{LaNiO}}_3\right)}_{\mathrm{n}}/{\left({\mathrm{LaMnO}}_3\right)}_{\mathrm{n}}\right]}_{\mathrm{M}}/{\mathrm{SrTiO}}_3\left(111\right)$ superlattices [$n=20$, 10, 5, 2, and 1 unit cells (u.c.)] as “precursor” heterostructures for a double perovskite ${\mathrm{La}}_2{\mathrm{NiMnO}}_6$. A charge transfer at the ${\mathrm{LaNiO}}_3$/${\mathrm{LaMnO}}_3$ interfaces and formation of the emergent ${\mathrm{La}}_2{\mathrm{NiMnO}}_6$ phase with ${\mathrm{Ni}}^{2+}$ and ${\mathrm{Mn}}^{4+}$ oxidation states was evidenced by in situ optical ellipsometry and supported by magnetic and Raman measurements. The 10/10 and 5/5 superlattices revealed a complex magnetic behavior with two ferromagnetic phase transitions with $T_{\mathrm{C}\text{−}\mathrm{low}}=170\mathrm{K}$ and $T_{\mathrm{C}\text{−}\mathrm{high}}\sim 250–280\mathrm{K}$, originating from the ferromagnetic ${\mathrm{LaMnO}}_3$ and the emergent interfacial ${\mathrm{La}}_2{\mathrm{NiMnO}}_6$ phase, respectively. With decreasing thickness of individual layers, the magnetism of 2/2 and 1/1 superlattices transforms into that of the ordered double perovskite ${\mathrm{La}}_2{\mathrm{NiMnO}}_6$. Furthermore, a structural reconstruction into a monoclinic $\left(P_{12}\right)$ structure of the ordered ${\mathrm{La}}_2{\mathrm{NiMnO}}_6$ at the interface, evidenced by Raman spectroscopy, goes ahead with the charge transfer and magnetic ${\mathrm{La}}_2{\mathrm{NiMnO}}_6$ behavior.