Diffusion of phonons in
LiY1-xHoxF4
P. J. Rump, A. F. M. Arts, and H. W. de Wijn
Faculty of Physics and Astronomy, and Debye Research Institute, Utrecht
University, P.O. Box 80.000, 3508 TA Utrecht, The Netherlands
The evolution in time and space of a nonequilibrium phonon distribution is
studied at various frequencies in
LiY1-xHoxF4 (x =
0.01, 0.03, and 0.1), a system featuring a series of closely lying
one-phonon transitions in the ground multiplet of the Ho3+ ion.
The frequency and concentration dependence of the derived diffusion
coefficient is reproduced by numerical simulations including elastic
scattering by localized centers and relaxation by three-phonon
interactions.