Observation of the 169Tm and 27Al NMR in Thulium Aluminum Garnet

Abstract

The observations of the ¹⁶⁹Tm and ²⁷Al nuclear magnetic resonances (NMR) in a single crystal of cubic thulium aluminum garnet are reported. The ²⁷Al MNR was studied between 1.5° and 300°K, while the ¹⁶⁹Tm NMR was observed only for T169Tm 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 e²qQ/h for the a and d sites were measured to be (0.892±0.005) and (6.155±0.005) MHz, respectively. The ²⁷Al NMR frequency shifts for both sites were found to be angular and temperature dependent. A calculation for the observed angular dependences of the ²⁷Al NMR frequency shifts in terms of dipolar fields is found to give reasonable agreement with experiment for the 1.5° and 300°K NMR data.