Optically-addressable spins in hexagonal boron nitride at room temperature

Optically addressable spins in materials are important platforms for quantum technologies, such as repeaters and sensors. Identification of such systems in two-dimensional (2d) layered materials offers advantages over their bulk counterparts, as their reduced dimensionality enables more feasible on-chip integration into devices. Here, we report room-temperature optically detected magnetic resonance (ODMR) from previously identified carbon-related single defects in 2d hexagonal boron nitride (hBN). We show that single-defect ODMR contrast is up to 100x stronger than that of ensembles and displays a magnetic-field dependence with both positive or negative sign per defect. Further, the ODMR lineshape comprises a doublet resonance, indicating a S=1 state with low but finite zero-field splitting. Our results offer a promising route towards realising a room-temperature spin-photon quantum interface in hexagonal boron nitride.