(Invited) Optical and Magnetic Properties of Defective MgO Microcrystals

Micrometer-sized MgO crystals are prepared by solid phase reaction between Mg and B2O3. The MgO microcrystals exhibit efficient photoluminescence (PL) emissions derived from oxygen vacancies, showing broadband laser emission at room temperature. Also, room temperature ferromagnetism is observed in the lasing MgO microcrystals. Ferromagnetic coupling between the surface magnesium vacancies via the surface low-coordinated oxygen atoms is suggested to explain the observed magnetic behavior.