Isotopic Control of the Boron-Vacancy Spin Defect in Hexagonal Boron Nitride

Abstract

We report on electron spin resonance (ESR) spectroscopy of boron-vacancy (VB-) centers hosted in isotopically engineered hexagonal boron nitride (hBN) crystals. We first show that isotopic purification of hBN with N15 yields a simplified and well-resolved hyperfine structure of VB- centers, while purification with B10 leads to narrower ESR linewidths. These results establish isotopically purified hB10N15 crystals as the optimal host material for future use of VB- spin defects in quantum technologies. Capitalizing on these findings, we then demonstrate optically induced polarization of N15 nuclei in hB10N15, whose mechanism relies on electron-nuclear spin mixing in the VB- ground state. This work opens up new prospects for future developments of spin-based quantum sensors and simulators on a two-dimensional material platform.