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.

A commonly believed picture of colossal magnetoresistance (CMR) effect is related to a first-order phase transition and electronic phase separation with coexisting ferromagnetic metallic and antiferromagnetic insulating phases. However, the underlying mechanism, i.e., the characteristic energy scale of the interacting phases and their spatial extent, is still under debate. Here we present experimental evidence on the existence of an effective antiferromagnetic coupling between the ferromagnetic nanodomains in epitaxial thin films of a classical CMR material (La${}_{1$-${}y}$Pr${}_{y}$)${}_{0.67}$Ca${}_{0.33}$MnO${}_{3}$ with Pr doping, $y$ = 0.375 and 0.4. This coupling yields to peculiar low-field CMR behavior with magnetic hysteresis and slow resistance relaxation, both induced by the magnetization reversal. The coercive field obeys a square-root temperature dependence for $T$\ll${}{T}_{\mathrm{C}}$ and increases anomalously close to the phase transition. We modeled the magnetic structure within the phase-separation scenario as an assembly of single-domain ferromagnetic nanoparticles, antiferromagnetically coupled (pinned) by correlated Jahn-Teller polarons. The concentration of polarons increases drastically close to phase transition as indicated by the third harmonic of the electrical conductivity as well as Raman spectroscopy.

We present a novel setup to measure the transverse magneto-optical Kerr effect in the extreme ultraviolet spectral range based on a fiber laser amplifier system with a repetition rate between 100 and 300 kHz, which we use to measure element-resolved demagnetization dynamics. The setup is equipped with a strong electromagnet and a cryostat, allowing measurements between 10 and 420 K using magnetic fields up to 0.86 T. The performance of our setup is demonstrated by a set of temperature- and time-dependent magnetization measurements with elemental resolution.

We report magneto-dielectric properties of partially B-site ordered monoclinic ${\mathrm{Tb}}_2\mathrm{CoMn}{\mathrm{O}}_6$ double perovskite thin film epitaxially grown on $\mathrm{Nb}:\mathrm{SrTi}{\mathrm{O}}_3$(100) substrates by metalorganic aerosol deposition technique. Transmission electron microscopy and electron energy loss spectroscopy mapping shows the presence and distribution of both $\mathrm{C}{\mathrm{o}}^{2+}$ and $\mathrm{C}{\mathrm{o}}^{3+}$ ions in the film, evidencing a partial $B$-site disorder, which was further confirmed by the observation of reduced saturation magnetization at low temperatures. The ferromagnetic Curie temperature, $T_C=110\mathrm{K}$, is slightly higher as compared to the bulk value (100 K) probably due to an in plane epitaxy tensile strain. Temperature dependent dielectric study reveals an unexpected high temperature dipolar relaxor-glass-like transition at a temperature $T^{*}\sim 190\mathrm{K}>T_{\mathrm{C}}$, which depends on the applied frequency and indicates a superparaelectric behavior. Two different dielectric relaxation peaks have been observed; they merge at $T^{*}$ where likely a coupling to the disorder-induced short range charge-spin correlations results in a 4% magneto-dielectric coupling.