Motion of positively charged muonium in ZnO


Baker B. B. , Lichti R. L. , Celebi Y. G. , Mengyan P. W. , Bani-Salameh H. N.

PHYSICA B-CONDENSED MATTER, vol.407, no.15, pp.2864-2866, 2012 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 407 Issue: 15
  • Publication Date: 2012
  • Doi Number: 10.1016/j.physb.2011.08.026
  • Title of Journal : PHYSICA B-CONDENSED MATTER
  • Page Numbers: pp.2864-2866

Abstract

We report on a study of the motional characteristics of positively charged muonium defect centers in ZnO as an analog for H+ behavior. Muon spin depolarization measurements at zero applied magnetic field were completed from 20 K to 400 K, with preliminary results to 750 K. Results at the lower temperatures imply that Mu(+) occupied two sites, and indicate local motion as thermally assisted tunneling with a characteristic energy of similar to 60 meV, as well as a site change transition above 200 K with barrier energy similar to 440 meV. Based on theoretical results, we have tentatively assigned these features to tunneling among three equivalent oxygen anti-bonding sites (AB(perpendicular to)) and a transition to a lower-energy bond-centered site (BC parallel to) oriented along the c-axis. Preliminary fits suggest that global diffusion of muonium occurs above 400 K, with a diffusion barrier energy of similar to 0.7 eV. Published by Elsevier B.V.