Quadrupole and paramagnetic interactions of 27Al nuclei in mixed yttrium-dysprosium-aluminum garnets Y3−x DyxAl5O12

Electron spin dynamics of Ce3+ ions in YAG crystals studied by pulse-EPR and pump-probe Faraday rotation

“…12(a neighboring Al ions. Indeed, as we have shown in the previous section, the electron spin dynamics of the 4f state is strongly influenced by the interaction with 27 Al nuclei (Fig. 6).…”

“…6(a) results from the coherent precession of the coupled electron-nuclear spins, which evidences the interaction between the unpaired electron of Ce 3+ and the surrounding 27 Al nuclei. The aluminum nuclei which possess a nonzero electric quadrupole moment were extensively used to probe the local charge distribution in YAG crystals [7,[25][26][27]. The effective Hamiltonian for analyzing the interaction with the 27 Al nuclei (I = 5/2) can be written in the form:…”

“…One can see that the damping rate increases near the frequency range of the aluminum Larmor precession. The electron-nuclear cross-relaxation transitions in the rotating reference frame become more efficient at the 27…”

“…where S is the electron spin operator, Q i is a traceless matrix, A i the hyperfine interaction tensor, I i nuclear spin operator of interaction with i-th aluminum nucleus, µ N the nuclear magneton, g N the nuclear g factor of 27 Al and the applied magnetic field orientation is θ = 90 • . Summation on i is for three magnetically nonequivalent positions of Al.…”

Solid-state NMR and short-range order in crystalline oxides and silicates: a new tool in paramagnetic resonances

“…For static (nonspinning) single crystals (or powders), the effects of paramagnetic cations are most likely dominated by large through-space dipolar couplings, which have long been measured to provide information on site occupancies. For example, in the 1 H and 19 F spectra of micas, the intensities of small dipolar-shifted resonances provided unique constraints on nonrandom association of Fe 2+ with OH À versus F À anions (Sanz & Stone, 1979); numerous 27 Al NMR studies of single crystals of yttrium aluminum garnet (YAG) laser materials with various paramagnetic (and optically active) rare earth dopants have indicated that random dodecahedral site mixing prevails (Charnaya et al, 1999;Vorob'ev et al, 1998), following an early report on an FeO-rich natural silicate garnet (Ghose, 1964). More modern approaches to high-resolution paramagnetic NMR, particularly in biomolecular solids, have been recently reviewed (Pintacuda & Kervern, 2013).…”