First-principles characterization of the nitrogen vacancy center in 4H-SiC

Silicon carbide is an industrially mature host material of promising spin defects, including the nitrogen vacancy (NV) center, for which coherent control at room temperature in the 4H polytype [1] has been recently demonstrated. However, the electronic properties of this center are still controversial, as conflicting experimental and computational results [2-3] have been reported in the literature. We report density functional theory calculations and spectrally resolved optically detected magnetic resonance measurements of NV in 4H-SiC, which in agreement with each other and with one recent report [3]. We find that the calculations agree with experiment only when we consider large supercells (>2000 atoms) and eliminate any spurious source of strain in the calculations. In addition, we compute zero-field splitting, hyperfine and quadrupole tensors to build a spin Hamiltonian and we compute coherence times. We find significant enhancement in T₂ and T₂* for basal defects compared to the axial ones, and we discuss similarities and differences with the corresponding quantities obtained for the divacancy in SiC.

[1] Wang, J.-F. et al. Phys. Rev. Lett 124, 223601 (2020).
[2] Csóré, A. et al. Phys. Rev. B 96, 085204 (2017).
[3] Zargaleh, S. A. et al. Phys. Rev. B 98, 214113 (2018).