Comment on "Generalization of the Abragam relaxation function to a longitudinal field"

Abstract

The muon spin relaxation technique (\ensuremath{\mu}SR) has proven to be a powerful experimental tool for the investigation of light interstitial diffusion in metals and magnetic phenomena. In order to deduce, from the \ensuremath{\mu}SR data, information on the physical properties of the investigated system a model is needed for the measured depolarization function. Recently Keren [Phys. Rev. B 50, 10 039 (1994)] has proposed an analytic result (AR) for the muon relaxation function in a dynamical magnetic environment and an external longitudinal field. He argues that his result is valid in the motional-narrowing limit or at the early time. In this comment we point out that the applicability of the proposed AR to real systems is limited because it does not incorporate some basic physical facts.