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

Description

Color centers in semiconductors, such as the NV-center in diamond, the silicon vacancy, and the di-vacancy in 4H-silicon carbide (4H-SiC), are potential candidates for quantum bits (qubits). Manipulating the spin optically involves exciting the fundamental high-spin multiplets and intersystem crossing (ISC), mediated by spin-orbit, spin-spin, and spin-phonon couplings. These interactions, together with the zero-field splitting of ground and excited states, enable various spin-photon protocols. For optimal engineering of such interfaces, a comprehensive understanding of spin-selective interactions and resulting spin-relaxation pathways is pivotal. Recent experiments regarding the VSi in 4H-SiC have revealed spin-dependent lifetimes and intercrossing rates using an effective model that considers only one or two instead of the five predicted intermediate doublet states [1]. Here we address this issue. We employ our extended CI-cRPA embedding approach for correlated defect states [2] to calculate the relevant spin-coupling parameters. We present a fine structure of the quartet states of consistent with existing literature. Based on our calculations, we discuss the ISC and spin-relaxation paths. In particular, we calculate ISC-rates for the two spin components that are in agreement with the experimental findings [1]. The calculated rates provide insight into the underlying role of the different intermediate states and indicate handles for engineering approaches. References [1] N. Morioka, et al., Phys. Rev. Appl. 17, 054005 (2022). [2] M. Bockstedte, et al., npj Quant Mater 3, 31 (2018).

Period	31 Jul 2024
Event title	e 816. WE-Heraeus-Seminar: Silicon Carbide: Classical and Quantum Technologies
Event type	Conference
Location	GermanyShow on map