Research Data for the publication titled "Impact of irradiation conditions on the magnetic field sensitivity of spin defects in hBN nano flakes"

Abstract for the paper : We study V_B⁻ centres generated by helium focused ion beam (FIB) irradiation in thin (~70 nm) hBN nanoflakes, in order to investigate the effect of implantation conditions on the key parameters that influence the magnetic field sensitivity of V_B⁻ quantum sensors. Using a combination of photoluminescence, optically detected magnetic resonance, and Raman spectroscopy, we examine the competing factors of maximizing signal intensity through larger V_B⁻ concentration against the degradation in spin coherence and lattice quality observed at high ion fluences.Our results indicate that both the V_B⁻ spin properties and hBN lattice parameters are largely preserved up to an ion fluence of 10¹⁴ ions cm⁻², beyond which significant degradation occurs in both. At the optimal implantation dose, an AC magnetic sensitivity of approximately 1 μT / √Hz is achieved. Using the patterned implantation enabled by the FIB, we find that V_B⁻ centres and the associated lattice damage are well localized to the implanted regions. This work demonstrates how careful selection of fabrication parameters can be used to optimize the properties of V_B⁻ centres in hBN, supporting their application as quantum sensors based in two-dimensional materials.