NAVAL RESEARCH LAB WASHINGTON DC WASHINGTON United States
We report T2 spin coherence times for electronic states localized in Si vacancies in 4HSiC. Our spin coherence study included two SiC samples that were irradiated with 2 MeV protons at different fluences 10exp 13 and 10exp 14cmexp -2 in order to create samples with unique defect concentrations. Using optically detected magnetic resonance and spin echo, the coherence times for each sample were measured across a range of temperatures from 8 to 295 K. All echo experiments were done at a magnetic field strength of 0.371 T and a microwave frequency of 10.49 GHz. The longest coherence times were obtained at 8 K, being 270 or - 61 microsecond for the 10exp 13cmexp -2 proton-irradiated sample and 104 or - 17 microsecond for the 10exp 14cmexp -2 sample. The coherence times for both samples displayed unusual temperature dependencies in particular, they decreased with temperature until 60 K, then increased until 160 K, then decreased again. This increase between 60 and 160 K is tentatively attributed to a motional Jahn-Teller effect. The consistently longer lifetimes for the 10exp 13cmexp -2 sample suggest that a significant source of the spin dephasing can be attributed to dipole-dipole interactions between Si vacancies or with other defects produced by the proton irradiation. The lack of a simple exponential decay for our 1014cm2 sample indicates an inhomogeneous distribution of defect spins.
Journal Article - Open Access
Physical Review B , 95, 4, 01 Jan 0001, 01 Jan 0001,