Negatively charged muonium states in gallium nitride

Muon nuclear-quadrupole level-crossing resonances (QLCR) and zero-field muo n spin depolarization functions are identified for negatively charged muoni um (Mu(-)) centers in wurtzite-structured GaN,The QLCR spectra imply that M u(-) occupies interstitial locations next to Ga atoms, consistent with the two inequivalent Ga anti-bonding sites. Mu(-) related depolarization shows an increase in average dipolar fields near 200K and indicates motion above 500K, Transitions suggested by relaxation features are briefly discussed. ( C) 1999 Elsevier Science B.V. All rights reserved.