Edge effects on optically detected magnetic resonance of vacancy defects in hexagonal boron nitride

The chemical and structural nature of defects responsible for quantum emission in hexagonal boron nitride (h-BN) remain unknown. Optically detected magnetic resonance (ODMR) measured from these defects was reported in two recent papers. In one case, the ODMR was tentatively attributed to the negatively charged boron vacancy, V-(B) over bar. Here we show how the key optical and magnetic properties vary with location within the bulk and along edges of h-BN sheets for this and the negatively charged nitrogen vacancy, V-(N) over bar. Sign changes of the axial zero-field interaction parameter D are predicted, as well interchange of singlet and triplet ground states. Based on the latest experimental information, we assign the observed ODMR signal to bulk V-(B) over bar. The other observed ODMR has some features reminiscent of our calculations for V-(N) over bar edge defects.