Frequency shifts and local spin susceptibility of muonium in heavily-doped Si and GaAs

We report high transverse field μSR measurements in heavily doped p-type Si as well as p-type and n-type GaAs. In all these samples, the precession frequencies due to diamagnetic Mu+ and Mu- are within ∼10 ppm of the Larmor frequency of the bare muon. In contrast to heavily doped n-type Si, no metastable neutral muonium centers are observed