Magnetic properties of a new spintronic material—GaN:Fe

We report on metal-organic chemical vapour deposition growth of GaN:Fe and its characterization by means of high-resolution X-ray diffraction, secondary ion mass spectroscopy, electron spin resonance, and magnetization measurements. Electron spin resonance studies demonstrate the existence of Fe in the isolated 3d5 (Fe3+) state. Magnetic measurements reveal, apart from Curie paramagnetism due to Fe3+, a temperature independent contribution which we attribute tentatively to van Vleck paramagnetism of Fe in the 2+ state. We conclude that the Fe ions coexist in two charge states in the investigated samples. The fraction of Fe3+ ions was found to increase upon additional co-doping with Mg acceptors, both in ESR as well as in magnetization measurements.