Sputtered Sm–Co films: Microstructure and magnetic properties

Abstract

Films of Sm–Co have been sputtered on heated polycrystalline Al2O3 substrates. The effect of variations of the Sm content on microstructure and hard magnetic properties was studied for otherwise constant process parameters. As generally observed, the samples possess a magnetic texture where the easy magnetization directions of the grains lay preferably in the film plane. For a lower Sm content the TbCu7-type structure is stabilized and for a higher Sm content the CaCu5-type structure is stabilized. The crossover occurs for a Sm content of around 17 at. %. Consistent with the changes in the intrinsic properties, coercivity increases and remanence decreases with increasing the Sm content. The grain size increases with increasing the Sm content and is attributed to a higher surface mobility during crystallization and grain growth. This behavior is also assumed to cause the improvement in the in-plane texture with increasing the Sm content, that had been quantified by magnetic and crystallographic investigations.