Carrier-mediated ferromagnetism in single crystalline (Co, Ga)-codoped ZnO films

Metallic (Co, Ga)-codoped ZnO single crystalline films have been grown by molecular beam epitaxy. Besides room temperature ferromagnetism, the anomalous hall effect (AHE) due to spin-orbit interaction was also found. The small AHE signals match quantitatively with the magnetic hysteresis and can be correspondent to the intrinsic ferromagnetism in a true diluted magnetic oxide with charge carrier spin polarization. Both the saturation magnetization and AHE can be significantly enhanced by additional carrier doping, revealing that the ferromagnetism is carrier mediated in (Co, Ga)-codoped ZnO films.