Muon/Muonium in an Isotopically Pure 13C Diamond

A preliminary study of the diamagnetic (μd) and the paramagnetic (Mu T ) states in a synthetic 13C diamond has been performed using the Transverse Field Muon Spin Rotation method. This system could be used to verify the quantum diffusion behaviour observed before, however, with a more reliable extraction of the hopping rate. The results were obtained in an applied magnetic field of 7.5 mT and at sample temperatures of 10 K, 100 K and 200 K. The prompt fraction, f, of the μd state remains constant at 22(5)% in the range 10–200 K; that of the Mu T state increases from 53(10)% at 10 K to 78(10)% at 200 K. The fractions of the two states add to 100% at 200 K, suggesting non-population of the bond-centred state, MuBC, which is often observed in other diamond samples. The μd state has a spin relaxation rate of 0.20(5) μs−1, in contrast to the zero value obtained in type II diamond samples. This indicates appreciable interaction of the μd state with the 13C atoms. The Mu T state has a large spin relaxation rate ranging from 3.0(5) μs−1 at 10 K to 7.0(5) μs−1 at 200 K, consistent with values obtained in diamond samples with defects. This work is part of ongoing studies of muon/muonium-defect interactions in diamonds.