Phonon contribution to nuclear spin diffusion in ruby crystal estimated by lattice dynamics calculations
Laboratoire Matériaux Avancés et Phénomènes Quantiques, Faculté des Sciences de Tunis, Université de Tunis El Manar, Campus Universitaire, 2092, Tunis, Tunisia
Accepted: 25 April 2022
Published online: 5 May 2022
Lattice dynamics calculations can evaluate the effect of lattice vibrations on the spin diffusion process in ruby crystal . The theory of Raman spin diffusion process is presented in an appropriate form to calculate the spin diffusion rate W using realistic phonon density of states. The coupling of nuclear spins to the phonon field establishes a temperature dependence of the spin diffusion rate, unlike the spin diffusion in a rigid lattice, where the rate is considered temperature independent. Therefore, the temperature dependence of Raman spin diffusion rate W(T) of is computed from realistic phonon density of states and compared to that obtained from the Debye function . We show that the use of realistic phonon spectrum in computation of W(T) leads to better result by an order of magnitude. Our measurement of the temperature dependence of impurity nuclear spin–lattice relaxation rate of between 77 and 303 K reveals the important role of phonons in spin diffusion process.
© The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2022