First-principles calculation of a negatively charged boron-vacancy center in diamond

Abstract

As the boron doping in diamond has been well established, and a negatively charged boron-vacancy (BV) center has an active electron paramagnetic resonance, the BV center is an attractive candidate for spin information devices. Using the first-principles calculation, we report the electronic structure of the BV center in diamond for its various charge states. A geometrically optimized BV center in the diamond supercell exhibited C 3v symmetry. The BV +1 charge state did not exhibit any spin splitting defect levels, while the BV 0 and BV %2 charge states showed a small energy separation between spin-polarized states. On the other hand, the negatively charged BV %1 center possesses bound states with a larger separation inside the diamond bandgap. Moreover, it has the spin-triplet ground state and the spin-conserved triplet excited state. These characteristics indicate that the BV %1 center in diamond is a good candidate for qubit operation.

Negatively charged boron vacancy center in diamond

“…Spin-selective intersystem crossing (ISC) from 3 E to 1 A 1 caused by the phonon-mediated spin-orbit coupling is crucial in its efficient optical spin polarization [58,59]. First-principles calculations on BVpredicted the spin-conserving transition from a 3 A 2 triplet ground state to a 3 E triplet excited state; however, its intermediate singlet states were not calculated [37,38]. Our observation indicates that the BVcenter has intermediate singlet state(s), common to the NVsystem.…”

“…1(c), the BVcenter with four valence electrons also realizes a spin-1 system with the e x and e y levels [32,37,38], which is exactly identical to those of NVand OV 0 . First-principles calculations predicted that the BVcenter is optically active with a triplet ground state and a triplet excited state in the band gap, suggesting it is a promising spin qubit [37,38]. Since both boron and nitrogen atoms are the most major impurities in diamond, the BVcenter might have potential comparable to that of the promising NVcenter.…”

“…On the other hand, a new family of NV --like defects possessing C 3v symmetry with a pair of substitutional impurity and adjacent vacancy and triplet (S = 1) ground states has been searched for by replacing the nitrogen atom with a firstrow element such as oxygen [32][33][34][35][36] and boron [32,37,38]. Figure 1(a) to 1(c) show schematic views of the one-electron state levels for the family of NV -, OV 0 , and BV -, respectively * Corresponding author: umeda.takahide.fm@u.tsukuba.ac.jp (see Appendix A for details).…”

“…In the OV 0 center, a 1 and a 1 are rewritten by 1a 1 and 2a 1 , respectively, and another a 1 state (denoted by 3a 1 ) is generated from an antibonding state of C-O bonds with three back-bonded carbon atoms [35]. Their energy positions are approximately shown in a band diagram [1,32,[35][36][37], where E C and E V are the conductionband top and the valence-band bottom, respectively.…”

Hemisorption of hydrogen on the diamond surface containing a "boron + vacancy" defect

“…According to ab initio calculations, the B 4 V-and BV-complexes correspond to the lowest energy of formation attributed to a single B atom. In [3], the authors study the electronic structure of a BV-center in diamond for its various charge states -BV 0 , BV +1 , BV −1 and BV −2 -using first-principles calculations. The charge state of the BV −1 complex defect is stable and is suitable for qubit realization.…”