Isotopic control of the boron-vacancy spin defect in hexagonal boron nitride

Abstract

We report on electron spin resonance (ESR) spectroscopy of boron-vacancy (V${}_{\text{B}}^{-}$) centers hosted in isotopically-engineered hexagonal boron nitride (hBN) crystals. We first show that isotopic purification of hBN with ${}^{15}$N yields a simplified and well-resolved hyperfine structure of V${}_{\text{B}}^{-}$ centers, while purification with ${}^{10}$B leads to narrower ESR linewidths. These results establish isotopically-purified h${}^{10}$B${}^{15}$N crystals as the optimal host material for future use of V${}_{\text{B}}^{-}$ spin defects in quantum technologies. Capitalizing on these findings, we then demonstrate optically-induced polarization of ${}^{15}$N nuclei in h${}^{10}$B${}^{15}$N, whose mechanism relies on electron-nuclear spin mixing in the V${}_{\text{B}}^{-}$ ground state. This work opens up new prospects for future developments of spin-based quantum sensors and simulators on a two-dimensional material platform.

6 pages, 3 figure