Investigation on the crystal structure, magnetic, and electrical transport properties of magnetron sputtered Co₂FeGe Heusler alloy films

Abstract Crystal structure, magnetic, and electrical resistivity behaviour of Co2FeGe Heusler alloy films deposited at different sputtering parameters have been studied using X-ray diffraction, VSM, and standard four-probe techniques. Though the expected structure was L21, X-ray diffraction studies indicate the A 2-type disordered structure. All films exhibited soft ferromagnetic characteristics having a coercive field of 5-65 Oe and a high ferromagnetic ordering temperature (More than 700 K). The electrical resistivity of the films deposited on the Si substrates was influenced by the substrate temperatures. Out of the different scattering mechanisms present in the low and high-temperature regimes, the two-magnon scattering effect is dominant in all the films. The scattering mechanisms are the same in all films irrespective of the substrate temperature. The optimum sputter deposition parameters that yields good quality Co2FeGe Heusler alloy thin films were found to be 50 W power, 5 mTorr pressure, and 400 °C substrate temperature.