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The use of magnetic garnets in new technologies such as spintronic devices requires fine-structured thin films. Classical fabrication techniques for these materials, typically physical vapor deposition methods, lead to excellent magnetic behavior. However, availability and scalability for potential applications are well restricted. In this study, we propose an innovative approach to fabricating Yttrium Iron Garnet thin films with precise thickness control achieved through iterative layer deposition via a chemical synthesis route. Remarkably, the iterative deposition process results in films exhibiting exceptional crystallinity. Magnetic characterization provides saturation magnetization and coercivity values on par with those reported in literature, summed to narrow ferromagnetic resonance lines. Therefore, in this work we demonstrate the viability of polymer assisted deposition as a promising alternative thinking about scalability to conventional deposition techniques for this material. Notably, our findings reveal energy conversion efficiencies comparable to those achieved with materials synthesized via physical vapor deposition methods.

Oxide spinels of general formula AB2O4 (A = Mg2+, Fe2+; B = Al3+, Cr3+, etc.) constitute one of the most abundant crystalline structures in mineralogy. In this structure, cations distribute among octahedral and tetrahedral sites, according to their size and the crystal-field stabilization energy. The cationic arrangement determines the mechanical, magnetic, and transport properties of the spinel and can be influenced by external parameters like temperature, pressure, or epitaxial stress in the case of thin films. Here, we report a progressive change in the sign of the Poisson ratio, ν, in thin films of CoFe2O4, defining a smooth crossover from auxetic (ν < 0) to non-auxetic (ν > 0) behavior in response to epitaxial stress and temperature. Microstructural and magnetization studies, as well as ab initio calculations, demonstrate that such unusual elastic response is actually due to a progressive redistribution of Co2+ among the octahedral and tetrahedral sites of the spinel structure. The results presented in this work clarify a long standing controversy about the magnetic and elastic properties of Co-ferrites and are of general applicability for understanding the stress-relaxation mechanism in complex crystalline structures.

The spin Hall effect (SHE) provides an efficient tool for the production of pure spin currents, essentially for the next generation of spintronics devices. Giant SHE has been reported in Cu doped with 0.5% Bi grown by sputtering, and larger values are predicted for larger Bi doping. In this work, we demonstrate the possibility of doping Cu with up to 10% of Bi atoms without evidence of Bi surface segregation or cluster formation. In addition, YIG/BiCu structures have been grown, showing a spin mixing conductance larger that the one shown by similar Pt/YIG structures, reflecting the potentiality of these new materials.