Depth-resolved measurement of the Meissner screening profile in a niobium thin film from spin-lattice relaxation of the implanted β-emitter 8Li
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Date
2023-10-28
Journal Title
Journal ISSN
Volume Title
Publisher
AIP Publishing
Abstract
We report measurements of the Meissner screening profile in a Nb(300 nm)/Al2O3 thin film using 8Liβ-detected nuclear magnetic resonance (β-NMR). The NMR probe 8Li was ion-implanted into the Nb film at energies ≤ 20 keV, corresponding to mean stopping depths comparable to Nb’s magnetic penetration depth λ. 8Li’s strong dipole–dipole coupling with the host 93Nb nuclei provided a “cross-relaxation” channel that dominated in low magnetic fields, which conferred indirect sensitivity to the local magnetic field via the spin-lattice relaxation (SLR) rate 1/T1. From a fit of the 1/T1 data to a model accounting for its dependence on temperature, magnetic field, and 8Li+ implantation energy, we obtained a magnetic penetration depth λ0= 51.5(22) nm, consistent with a relatively short carrier mean-free-path ℓ= 18.7(29) nm typical of similarly prepared Nb films. The results presented here constitute an important step toward using 8Liβ-NMR to characterize bulk Nb samples with engineered surfaces, which are often used in the fabrication of particle accelerators. © © 2023 Author(s). Published under an exclusive license by AIP Publishing.
Description
Keywords
Niobium, Thin Films, Lithium, Spin-lattice relaxation, Electromagnetic fields, Data, Ion implantation, Superconductivity, Ion implantation, Nuclear magnetic resonance
Citation
McFadden, R. M. L., Asaduzzaman, M., Buck, T. J., Cortie, D. L., Dehn, M. H., Dunsiger, S. R., Kiefl, R. F., Laxdal, R. E., Levy, C. D. P., MacFarlane, W. A., Morris, G. D., Pearson, M. R., Thoeng, E., & Junginger, T. (2023). Depth-resolved measurement of the Meissner screening profile in a niobium thin film from spin-lattice relaxation of the implanted β-emitter 8Li. Journal of Applied Physics, 134(16), 163902. doi:10.1063/5.0175532