Relaxation dynamics of spin 3/2 silicon vacancies in 4H-Silicon carbide

TL;DR

This study investigates the relaxation dynamics of spin 3/2 silicon vacancies in 4H-Silicon carbide at room temperature, revealing three distinct relaxation modes and their measured times, which differ from idealized models.

Contribution

It provides the first experimental demonstration of three separate relaxation modes in a spin 3/2 system and measures their relaxation times, highlighting mode admixture.

Findings

Identified three distinct relaxation modes in spin 3/2 silicon vacancies.

Measured relaxation times: approximately 0.41 T_{slow} and 3.3 T_{fast}.

Observed deviations from ideal dipole, quadrupole, and octupole relaxation models.

Abstract

Room temperature optically detected magnetic resonance experiments on spin 3/2 Silicon vacancies in 4H-SiC are reported. The $m_s=+1/2\leftrightarrow -1/2$ transition is accessed using a two microwave frequency excitation protocol. The ratio of the Rabi frequencies of the $+3/2 \leftrightarrow +1/2$ and $+1/2\leftrightarrow -1/2$ transitions is measured to be $(0.901\pm 0.013)$. The deviation from $\sqrt{3}/2$ is attributed to small difference in g-factor for different magnetic dipole transitions. Whereas a spin-1/2 system is characterized by a single spin lifetime $T_1$, we experimentally demonstrate that the spin 3/2 system has three distinct relaxation modes that can be preferentially excited and detected. The measured relaxation times are $(0.41\pm 0.02) T_{slow}=T_d= (3.3\pm 0.5)T_{fast} $. This differs from the values of $ T_p/3 =T_d= 2T_f $ expected for pure dipole ($T_p$), quadrupole ($T_d$), and octupole ($T_f$) relaxation modes, respectively, and implies admixing of the slow dipole and fast octupole relaxation modes.