Creation of optically addressable spin centers in hexagonal boron nitride by proton irradiation

The possibility of creating defects with spin-dependent fluorescence in a Van der Waals material, hexagonal boron nitride (hBN), by irradiating the latter with high-energy protons ($E_P$ = 15 MeV) has been studied. Using micro-photoluminescence and electron paramagnetic resonance methods it was shown that such irradiation leads to the creation of boron vacancies in the negative charge state ($V^-_{\mathrm{B}}$-centers). The ground spin triplet ($S$ = 1) state of these defects demonstrates an optically induced inverse population. Keywords: electron paramagnetic resonance, micro-photoluminescence, hexagonal boron nitride, boron vacancy.