Photoluminescence at the ground state level anticrossing of the nitrogen-vacancy center in diamond

Abstract

The nitrogen-vacancy center (NV center) in diamond at magnetic fields corresponding to the ground state level anticrossing (GSLAC) region gives rise to rich photoluminescence (PL) signals due to the vanishing energy gap between the electron spin states, which enables to have an effect on the NV center's luminescence for a broad variety of environmental couplings. In this article we report on the GSLAC photoluminescence signature of NV ensembles in different spin environments at various external fields. We investigate the effects of transverse electric and magnetic fields, P1 centers, NV centers, and the 13 C nuclear spins, each of which gives rise to a unique PL signature at the GSLAC. The comprehensive analysis of the couplings and related optical signal at the GSLAC provides a solid ground for advancing various microwave-free applications at the GSLAC, including but not limited to magnetometry, spectroscopy, dynamic nuclear polarization (DNP), and nuclear magnetic resonance (NMR) detection. We demonstrate that not only the most abundant 14 NV center but the 15 NV can also be utilized in such applications and that nuclear spins coupled to P1 centers can be polarized directly by the NV center at the GSLAC, through a giant effective nuclear g-factor arising from the NV center-P1 center-nuclear spin coupling. We report on new alternative for measuring defect concentration in the vicinity of NV centers and on the optical signatures of interacting, mutually aligned NV centers.

Dipolar spin relaxation of divacancy qubits in silicon carbide

“…2. The curves are similar to those reported for the NV center in diamond interacting with substitutional nitrogen point defects 39,42 . However, in hexagonal SiC polytypes there is only one allowed symmetry distortion and the hyperfine interaction is dominantly isotropic 55 , which leads to a less complicated spin structures at B GSLAC /2.…”

“…36,37 Furthermore, optical signatures of strong environmental couplings were revealed, enabling novel microwave free spectroscopy applications. [38][39][40][41][42] In contrast, much less is known about the longitudinal spin relaxation of divacancy qubits in SiC. The T 1 time was reported for specific values of the magnetic field at various temperatures [43][44][45] , however, no systematic studies on the environmental couplings and resulting spin relaxation processes have been carried out yet.…”