**5. Conclusion**


annealed sample at 900°C is 10.7 (× 10−5 emug–1) while that for Co+ implanted sample is about 4.5 (× 10–5 emug–1). A higher value of *Ms* for Cr+ implanted GaN and annealed at 900°C suggests that samples implanted with Cr<sup>+</sup> ions may perform better for dilute magnetic semiconductors (DMSs) compared to Co<sup>+</sup> implanted. Also higher values of *Ms* for implanted samples may suggest again that 900°C is a suitable annealing temperature for the activation of dopants.

**7.** FC and ZFC measurements by SQUID were made on Co<sup>+</sup> and Cr+ implanted representative samples subsequently annealed at 900°C. The data did not indicate any blocking temperature that can be associated with superparamagnetic behaviour arising from undetected magnetic secondary phase clusters. Magnetization as a function of temperature showed the highest reported Curie temperature *T*<sup>C</sup> ∼ 370 K for Co+ implanted GaN and highest reported *T*C above the measured temperature (380 K) for Cr<sup>+</sup> implanted GaN. These findings are the highest reported Curie temperatures (*T*C) for Co+ and Cr+ implanted GaN diluted magnetic semiconductors (DMSs).
