Investigation of magnetic anisotropy in the Ni-Ge and Ni(NiO)-Ge thin films

We studied the structural and magnetic properties of Ni-Ge and Ni(NiO)-Ge films deposited by physical vapor deposition technique on the Si/SiO₂ substrate. The x-ray diffraction (XRD) analysis show that as-prepared samples exhibit clear peaks of Ge, Ni, and Au with a cubic symmetry belongs to space group Fm3̅m. Due to the thermal annealing process at 350°C, NiO layer formed on Ni layer. The NiO formation has reduced the interaction of Ni-Ge interlayer which is confirmed by XRD data. Investigation of temperature-dependent magnetic moment revealed the Neel and the critical temperatures as 93 and 294 K, respectively. The hysteresis loops showed that the preferred magnetization direction for samples at 300 K is the in-plane (parallel) which reaches saturation easier than out-of-plane (perpendicular) loops. The formation of NiGe interlayer resulted in a magnetically dead-region which led to decrease ferromagnetic domain and the coercive field.