Browsing by Author "Jones, E. D."

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Nuclear-Magnetic-Rosonance Study of Thulium Aluminum Garnet
(1970-03) Jones, E. D.; Schmidt, V. Hugo
The Tm169 and the Al27 nuclear magnetic resonance have been studied in cubic thulium aluminum garnet. The Tm169 results at 1.5°K give magnetic-susceptibility tensor components of χ1=0.014, χ2=0.551, and and χ3=0.030 emu/g ion, which show much more anisotropy than found previously for thulium gallium garnet. The measured Al27 paramagnetic shifts at 1.5°K agree quite well with values calculated from Tm3+-ion dipole sums. The Al27 paramagnetic shifts from 1.5 to 300°K are used to calculate the approximate temperature dependence of the Tm2+-ion susceptibility components. The room-temperature Al27 quadrupolar coupling constants ∣∣e2qQh∣∣ for the axially symmetric a and d sites are 0.892±0.005 and 6.155±0.005 MHz, respectively. The unshielded electric field gradients are calculated and compared with corresponding values for other aluminum garnets and for Fe57 sites in several iron garnets. These field gradients agree quite well with values calculated using a point-charge model.
Observation of the 169Tm and 27Al NMR in Thulium Aluminum Garnet
(American Institute of Physics, 1969-03) Jones, E. D.; Schmidt, V. Hugo
The observations of the 169Tm and 27Al nuclear magnetic resonances(NMR) in a single crystal of cubic thuliumaluminumgarnet are reported. The 27Al MNR was studied between 1.5° and 300°K, while the 169Tm NMR was observed only for T<4°K. From a study of the angular dependences of the 169Tm NMR fields, the (ξ, η, ζ) components of the Tm3+ susceptibility tensor were found to be highly ansiotropic and in units of emu/gram‐atom, χ1=0.014, χ2=0.551, and χ3=0.03. The room temperature 27Al nuclear quadrupolar coupling constants e 2 qQ/h for the a and d sites were measured to be (0.892±0.005) and (6.155±0.005) MHz, respectively. The 27AlNMR frequency shifts for both sites were found to be angular and temperature dependent. A calculation for the observed angular dependences of the 27AlNMR frequency shifts in terms of dipolar fields is found to give reasonable agreement with experiment for the 1.5° and 300°K NMR data.