Structural and magneto-transport properties of co-sputtered MnAl thin films

We report the structural and magneto-transport properties of co-sputtered MnAl alloy thin films grown on Si (1 0 0) at various substrate temperatures (T-s) ranging from room temperature to 500 degrees C. Analyses of the X-ray diffraction and DC-Magnetization data reveal that as the T-s of the films is changed, the volume fraction of ferromagnetic tau-MnxAl100-x (50 < x < 60) metastable phase retained in the films changes from 3.7 to 9.5% and the remaining fraction comprises of non-magnetic beta-MnAl and gamma(2)-phases. The temperature-dependent longitudinal resistivity variation demonstrates a semi-metallic nature in all these films. The temperature dependence of Hall Effect data further corroborates this semi-metallic behavior. The magnetoresistance (MR) response of these films is measured in the range of 10-300 K, both in the in-plane as well as out-of-plane magnetic field configurations. The out-of-plane MR is significantly larger than in-plane MR due to electron-hole compensation (which stems from mull-band effects) which is discussed further by plotting the Kohler's plot for the thin films.