Impact of Magnetic Adsorbates on Shallow Nitrogen-Vacancy Centers: Insights from Diamond C(001) Surface Studies

Using density functional theory calculations, we investigated the magnetization and magnetic anisotropy of O2, H, and OH adsorbates on diamond surfaces. Our findings reveal that these adsorbates possess significant magnetic moments, with O2 having 2.0 μB and H and OH having 1.0 μB, respectively. Furthermore, they exhibit a non-negligible exchange coupling with the spin of the nitrogen-vacancy (NV) center positioned a few layers beneath the surface. Given the extremely small magnetic anisotropy energies of all of these systems (<1.0 μeV), the presence of magnetic adsorbates is expected to introduce noticeable noise in NV sensing, particularly when NV centers are positioned closer to the surface