Structural and Magnetic Properties of Sm Implanted GaN

The structural and magnetic properties of Sm ion-implanted GaN with different Sm concentrations are investigated. XRD results do not show any peaks associated with second phase formation. Magnetic investigations performed by superconducting quantum interference device reveal ferromagnetic behavior with an ordering temperature above room temperature in all the implanted samples, while the effective magnetic moment per Sm obtained from saturation magnetization gives a much higher value than the atomic moment of Sm. These results could be explained by the phenomenological model proposed by Dhar et al. [Phys. Rev. Lett. 94(2005) 037205, Phys. Rev. B 72(2005) 245203] in terms of a long-range spin polarization of the GaN matrix by the Sm atoms.

Knowledge Innovation Project of Chinese Academy of Sciences YYYJ-0701-02 National Natural Science Foundation of China 60576046 60606002National Basic Research Program of China 2002CB311903 2006CB604905 513270605Supported by the Knowledge Innovation Project of Chinese Academy of Sciences under Grant No YYYJ-0701-02 the National Natural Science Foundation of China under Grant Nos 60576046 and 60606002 and the National Basic Research Program of China under Grant No 2002CB311903 2006CB604905 and 513270605.