Strontium hexaferrite SrFe12O19 (SFO) permanent magnets are widely used in electric motors and generators. But thin films are essential for many applications. We report on the influence of annealing of SFO films on Si(100)

 M-type ferrites are among the most popular permanent magnetic materials. This is mainly due to their high magnetocrystalline anisotropy which leads to elevated coercive fields. In addition, these hard ferrites exhibit excellent thermal and chemical stability, high Curie temperatures and good wear resistance, as well as being environmentally friendly and competitively priced products. These materials are widely applied for different uses, such as motors, magneto-mechanical devices and actuators, among others. The M-hexaferrite family is composed by strontium hexaferrite SrFe12O19 (SFO), barium hexaferrite BaFe12O19, and lead hexaferrite PbFe12O19. We have studied the influence of the annealing treatment on the crystalline growth of SrFe12O19 previously deposited on Si (100) substrates using radio frequency (RF) magnetron sputtering. For this goal, two grown films, with and without ex situ heating step, have been analyzed and compared to determine the differences in their structural, compositional, and magnetic properties. The results obtained by the different analysis techniques, in particular Mössbauer spectroscopy together with EXAFS and XANES data, suggest that the as-grown film is composed of nanocrystalline maghemite nanoparticles and amorphous strontium oxide. Specifically, Mössbauer spectroscopy results pointed out the presence of Fe3+ cations occupying octahedral and tetrahedral sites with hyperfine magnetic fields 49.3 T and 44.2 T, respectively, characteristic of a spinel-related structure. A strontium hexaferrite canonical structure with a c-axis orientation in the sample plane was found for the annealed film. G.D. Soria, A. Serrano, J.E. Prieto, A. Quesada, G. Gorni, J. de la Figuera, J.F. Marco, "Effect of annealing in the formation of well-crystallized and textured SrFe12O19 films grown by RF magnetron sputtering", Journal of Materials Research (2022).