Magnetic and electrical properties of ε-Fe N on c-plane GaN

ε-Fe N films on c-plane GaN are fabricated through nitridation of amorphous Fe films. From x-ray diffraction, the structures of these ε-Fe N films are found to consist of two crystal orientations of ε-Fe N, i.e. (002) and (111). The binding energies of Fe ions in the samples are analysed by x-ray photoelectron spectroscopy, both Fe-N and Fe-O-N peaks are observed. Scanning electron microscopy shows that the surface morphology of the ε-Fe N films is island-like. In particular, these films are ferromagnetic at room temperature, with a coercivity of about 200Oe according to the measured magnetic hysteresis loop. The ferromagnetism is further studied by ferromagnetic resonance spectra. With increasing angle between the incident field and the sample plane, the resonance magnetic fields of Fe and ε-Fe N films exhibit different behaviours; the difference can be interpreted by Kittel's theory. In addition, the I-V curves and Hall measurement indicate that the ε-Fe N films are good conductors at room temperature. On the whole, these magnetic and electrical properties demonstrate that the ε-Fe N films are appropriate for GaN-based spintronic devices. © 2012 IOP Publishing Ltd.