Positive muon diffusion and localization sites in GdNi5

GdNi5 is a simple metallic ferrimagnet with well understood magnetic proper ties. It has been used in the past as a testing ground for validating muon spin relaxation theories. Here we report on the muon diffusion and site loc alization in its paramagnetic phase, i.e., above 30.85 K. The muon localize s at the interstitial 3f sites over the whole temperature range. Below simi lar to 70 K the interstitial Gm sites become populated as well. These sites form a ring surrounding the (0,0,1/2) site and the muon can occupy ail the se sites within its lifetime. Above 40 K the muon residing time in these si tes is relatively short and it jumps to the 3f site by a quantum diffusion process. (C) 2000 Elsevier Science B.V, All rights reserved.