Nitrogen-vacancy-induced magnetism in AlN is investigated both theoretically and experimentally. First-principles calculations reveal that magnetic coupling between the vacancy-induced moments varies with the vacancy concentration. A sizable ferromagnetic coupling for nitrogen vacancies is found. Experimentally, the magnetism manipulation is realized accordingly by introducing vacancies through varying the nitrogen atmosphere in AlN whiskers. The vacancy control may be applicable to other III-V nitride semiconductors in tuning their magnetism.

Ferromagnetism is investigated in high-quality Cu-doped AlN single crystal whiskers. The whiskers exhibit room-temperature ferromagnetism with a magnetic moment close to the results from first-principles calculations. High crystallinity and low Cu concentrations are found to be indispensable for high magnetic moments. The difference between the experimental and theoretical moment values is explored in terms of the influence of nitrogen vacancies. The calculated results demonstrate that nitrogen vacancies can reduce the magnetic moments of Cu atom.