Identification of the spintronic NiGaVN center in c-GaN and its qubit applications

Abstract

The presence of NiGa center in cubic gallium nitride (c-GaN), a candidate material for qubit applications, has been proven through first-principles calculation and theoretical analysis. The NiGa center is composed of a nitride-vacancy (VN) and an adjacent substitutional nickel atom (NiGa) at the gallium site, possessing the same C 3v structure with the negatively charged nitrogen-vacancy center (NV– center) as the diamond. The NiGa center is a spin-triplet, existing in n-type c-GaN. Combined with the group theory, the molecular orbitals (MOs), and the electron distribution of the center were analyzed. Furthermore, regarding the optical properties of the NiGa center and maintaining spin-conserving, the electron occupation number in the MOs a 1(2) and exy could be changed, which opens up the prospects for spin manipulation in the NiGa center. As a result, the zero-phonon line is found to be relatively low (at about 0.575 eV), which means the optical excitation can be achieved at lower energy. The Stokes and anti-Stokes shifts are shown to be 240 and 153 meV, respectively. Therefore, the findings of this study provide an important basis for quantum computing and networks. In particular, combining the results of the magnetic coupling and hyperfine interaction to achieve the best characteristics of the spintronic center makes it promising for qubit application.