Structure and magnetic properties of films

A series of FexGe1−x ( x = 0 , 0.0097, 0.019, 0.038, 0.056, 0.073, 0.089, 0.105) thin films were prepared by magnetron sputtering. Physical property measurement system (PPMS) measurements showed that such films have ferromagnetic properties at room temperature and that the ferromagnetism arises from the interaction of the Fe spins, mediated by hole carriers. From the studies of X-ray diffraction (XRD) we find no secondary phases in the films. X-ray photoelectron spectrum (XPS) and X-ray absorption fine structure (XAFS) indicate that the Fe ions are in the 0 and the +2 state.