The Site and High Field βNMR Properties of 8Li+ Implanted in α-Al2O3

Abstract
We present high (> 2 T) magnetic field βNMR measurements of 8Li+ 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 8Li+ 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 βNQR spectra, where multiple singals are detected, only a single site is evident at high field. We discuss possible explanations for this discrepancy. The spin lattice relaxation is extremely slow (1/T1 < 0.02 s−1 ) over a broad temperature range from 4 to 300 K, demonstrating that cross relaxation with the 27Al nuclear spins is quenched in such high magnetic fields.
Description
Keywords
Magnetic fields, Monocrystals, Sapphire, Materials, Electric fields, Density
Citation
MacFarlane, W. A., Shenton, J. K., Salman, Z., Chatzichristos, A., Cortie, D. L., Dehn, M., Fujimoto, D., Karner, V. L., Kiefl, R. F., Koumoulis, D., Levy, C. D. P., McFadden, R. M. L., McKenzie, I., Morris, G. D., Pearson, M. R., Stachura, M., & Ticknor, J. O. (2022). The Site and High Field βNMR Properties of 8Li+ Implanted in α-Al2O3. Paper presented to The 15th International Conference on Muon Spin Rotation, Relaxation and Resonance 28/08 - 02/09/2022 Parma, Italy. In Journal of Physics: Conference Series 2023, V. 2462 (1), (pp. 012009_1 - 012009_11). DOI: 10.1088/1742-6596/2462/1/012009