Optically addressable spins in wide-bandgap semiconductors are a promising platform for exploring quantum phenomena. While colour centres in three-dimensional crystals such as diamond and silicon carbide were studied in detail, they were not observed experimentally in two-dimensional (2D) materials. Here, we report spin-dependent processes in the 2D material hexagonal boron nitride (hBN). We identify fluorescence lines associated with a particular defect, the negatively charged boron vacancy (\({\mathrm{V}}_{\mathrm{B}}^ -\)), showing a triplet (S = 1) ground state and zero-field splitting of ~3.5 GHz. We establish that this centre exhibits optically detected magnetic resonance at room temperature and demonstrate its spin polarization under optical pumping, which leads to optically induced population inversion of the spin ground state—a prerequisite for coherent spin-manipulation schemes. Our results constitute a step forward in establishing 2D hBN as a prime platform for scalable quantum technologies, with potential for spin-based quantum information and sensing applications.

宽带隙半导体中的光学可寻址自旋是探索量子现象的有前途的平台。虽然对金刚石和碳化硅等三维晶体中的色心进行了详细研究，但在二维 (2D) 材料中并未通过实验观察到它们。在这里，我们报告了二维材料六方氮化硼 (hBN) 中的自旋相关过程。我们识别与特定缺陷相关的荧光线，即带负电的硼空位 ( \({\mathrm{V}}_{\mathrm{B}}^ -\) )，显示三重态 ( S = 1) ~3.5 GHz 的基态和零场分裂。我们确定该中心在室温下表现出光学检测到的磁共振，并在光泵浦下展示其自旋极化，这导致自旋基态的光诱导粒子数反转——相干自旋操纵方案的先决条件。我们的结果在将 2D hBN 建立为可扩展量子技术的主要平台方面向前迈出了一步，具有基于自旋的量子信息和传感应用的潜力。