Transition dynamics for Mu acceptor states in $Si1–xGex$ alloys

We use the longitudinal field muon spin relaxation technique to observe charge-state and site-change transitions of muonium in $Si1–xGex$ alloys. In this project, we examine the temperature and magnetic field dependences of the relaxation rates for $Si1–xGex$ samples (x = 0.77, 0.81, and 0.84), in the composition range where the acceptor level lies within the band gap. This study particularly focuses on the relaxation rates for $Si0.19Ge0.81$ to identify various cyclic charge-state and site-change processes as a function of both temperature and magnetic field. We extract the paramagnetic hyperfine constant and the relevant transition rate parameters for site changes and charge-state transitions involving Mu acceptor states for this sample. At small x, a site change dominates the transition out of the neutral T-site acceptor state, while in higher Ge content alloys hole ionization becomes the dominant transition out of the $MuT0$⁠.