Oxygen-related muon species in crystalline silicon

A new muonium centre, termed Mu(X), with anisotropic hyperfine interaction has been discovered recently in crystalline silicon in transverse-field muon spin rotation experiments (Schefzik et al., Philos. Mag. B 79 (1999) 1561). Its hyperfine tensor is very close to that of bond centred muonium (Mu(BC)). The signature of Mu(X) is only observable in samples containing oxygen in a concentration which is higher than that of the donors or accepters. This indicates that Mu(X) is related to an oxygen-muonium centre. In the present work we have carried out a study of the temperature behaviour of the Mu(X) signal on a sample showing a very pronounced Mu(X) signature. The observations clearly show that the Mu(X) signal, on the one hand, and the Mu(BC) signals, on the other, have an identical temperature dependence. (C) 2000 Elsevier Science B.V. All rights reserved.