Physics

Paramagnetism

van der Waals force

Hyperfine structure

Resonance (particle physics)

Nanotechnology

Organic chemistry

Atomic physics

Chemistry

Unpaired electron

Electron paramagnetic resonance

Materials science

Condensed matter physics

Spins

Boron nitride

Molecule

Molecular physics

Nuclear magnetic resonance

Delocalized electron

Nature Materials

A plethora of single-photon emitters have been identified in the atomic layers of two-dimensional van der Waals materials1–8. Here, we report on a set of isolated optical emitters embedded in hexagonal boron nitride that exhibit optically detected magnetic resonance. The defect spins show an isotropic ge-factor of ~2 and zero-field splitting below 10 MHz. The photokinetics of one type of defect is compatible with ground-state electron-spin paramagnetism. The narrow and inhomogeneously broadened magnetic resonance spectrum differs significantly from the known spectra of in-plane defects. We determined a hyperfine coupling of ~10 MHz. Its angular dependence indicates an unpaired, out-of-plane delocalized π-orbital electron, probably originating from substitutional impurity atoms. We extracted spin–lattice relaxation times T1 of 13–17 μs with estimated spin coherence times T2 of less than 1 μs. Our results provide further insight into the structure, composition and dynamics of single optically active spin defects in hexagonal boron nitride. The optically detected magnetic resonance of a single defect in hexagonal boron nitride is reported.

Single-spin resonance in a van der Waals embedded paramagnetic defect