15th International Conference on Muon Spin Rotation, Relaxation and Resonance

The site and high field βNMR properties of 8Li+ implanted into α-Al2O3

P-MON-29

29 Aug 2022, 17:20

1h 40m

Science and Technology Campus, University of Parma

Poster Site calculations Posters

Speaker

Prof. Andrew MacFarlane (Chemistry Department, The University of British Columbia)

Description

We present high magnetic field $\beta$NMR measurements of ${}^8$Li${}^{+}$ implanted in single crystals of sapphire, a commonly used backing material for other samples. From the well-resolved quadrupolar splitting, we extract the electric field gradient (EFG) at the implanted ${}^8$Li${}^{+}$ site. Comparison with supercell density functional theory calculations of the EFG allows us to identify the octahedral interstitial site as the most likely candidate. In contrast to the zero field $\beta$NQR spectra, only a single site is evident at high field. We discuss possible explanations for this discrepancy. The high field spin lattice relaxation is extremely slow ($1/T_1<0.02$ s${}^{-1}$) from 4 to 300 K. This regime, where cross relaxation to the ${}^{27}$Al nuclear spins is quenched, extends down to at least 2.2 Tesla.