The influence of substrate orientation on the magnetic behavior of nearly-stoichiometric Mn5Ge3 thin films: DFT calculations and experimental analysis

The Mn5Ge3 exhibits a wide range of fascinating properties such as high spin polarization up to 42 %, large spindiffusion lengths, near-room Curie temperature, and possible integration with Ge, GaAs, and Si substrates. Theinfluence of substrate orientation on magnetic behavior has been investigated. The thin films studied present anin-plane magnetic reversal which is isotropic in samples grown on GaAs(111) and anisotropic in samples grownon GaAs(001). Another difference observed is a linear trend to saturation on the out-of-plane hysteresis loop insamples grown on GaAs(111), comparatively to samples grown on GaAs(001). To better understand this scenario,Density Functional Theory (DFT) calculations were conducted. The results indicate a ferromagnetic metallicground state with properties that are consistent with the experimental results. The projected densities of statesindicate that the main responsible for the magnetic moment observed in the Mn5Ge3 is the Mn-Mn interaction.The magnetic field distribution isosurfaces obtained from the DFT calculations offer a satisfactory explanation ofthe magnetic reversal experimentally observed, especially the in-plane magnetic behavior in samples grown onboth GaAs(111) and GaAs(001) substrates. This work provides a theoretical-experimental approach that allows adeeper understanding of the magnetic anisotropy behavior under the influence of the crystallographic orientationof the substrate observed in nearly-stoichiometric Mn5Ge3 thin films, which is a good candidate for rareearthfree magnet in spintronic applications.