DIFFUSION OF POSITIVE MUON IN PURE IRON .1. QUANTUM DIFFUSION

Diffusion constant of light particles in b.c.c. lattice is calculated on the basis of the self-trapping model. The hopping and the coherent motions of the particles are treated equally by extending the method of density matrix used by Kagan and Klinger in order to take account of the existance of several interstitial sites in a unit cell. With decrease of temperature, the diffusion constant shows an activation type decrease due to the hopping motion and turns increasing owing to the coherent motion. Temperature dependence of the hopping rate and role of an intra-site perturbation as a dominant scattering mechanism of the coherent motion are discussed in detail. It is shown that recent experimental results on spin relaxation time of positive muon in pure Iron can be understood in terms of the under-barrier hopping and possibly the coherent motion. © 1979, THE PHYSICAL SOCIETY OF JAPAN. All rights reserved.