Understanding the spin-selective transitions of defect spins ab initio theory of spin-spin and spin-orbit coupling

Description

Color centers in semiconductors with coupled spins, such as the NV center in diamond, the silicon vacancy (VSi), and the di vacancy (VCVSi) in silicon carbide (SiC), implement quantum bits for sensing and other quantum applications. Optical manipulation of the spin includes the excitation of the fundamental high-spin transition and spin-selective non-radiative relaxation via intermediate low-spin states facilitated by spin-spin and spin-orbit coupling. This and the zero-field splittings of the ground and excited states permit a variety of spin-photon protocols. Optimal engineering of such interfaces requires a deep understand the different spin-selective couplings and the resulting spin-relaxation paths. In the case of the silicon vacancy in SiC, recent experiments obtained spin dependent lifetimes and intercrossing rates based on an effective model with only one intermediate state instead of five theoretically predicted ones. Here we address the open question regarding the spin-relaxation mechanism using our embedding approach (CI-cRPA) based on configuration interaction and a screened electron-electron interaction derived from hybrid density functional theory. Our approach yields a fine structure of the quartet states of VSi consistent with literature and enables us to draw a quantitative picture of the spin-orbit coupling in the spin-relaxation path. Besides VSi, we also address the di-vancancy in SiC and the NV center in diamond.

Period	05 Mar 2024
Event title	unbekannt/unknown
Event type	Conference
Location	United StatesShow on map