Strong magnetization and anisotropy of Mn₅Ge₃thin films on Ge(001)

We report on the growth of Mn₅Ge₃thin films on Ge(001) substrates following two methods: solid phase epitaxy (SPE) and reactive deposition epitaxy (RDE). We have varied the thickness of the films, in order to study the magnetization and anisotropy evolution. A strongly enhanced magnetization of 1580 kA m^-1, compared to 1200 ± 150 kA m^-1for films grown on Ge(111), has been measured on ultrathin films of 5 nm grown by RDE. Thicker films exhibited magnetizations <750 kA m^-1. The films grown by SPE also exhibit strong magnetization of 1490 kA m^-1and a drop of magnetization by increasing the film thickness. The effective magnetic anisotropy exhibits a more complex behavior: increases on the SPE films and decreases on the RDE films while increasing the thickness of the films. Magnetostatic and interfacial anisotropies were considered and calculated. The results are discussed in terms of the growth methods and microstructure of the films.