Investigation of muon-state dynamics in silicon by longitudinal field-quenching and radio-frequency μ spin resonance

The two paramagnetic muon states-normal and anomalous muonium-and the diamagnetic muon states have been investigated in different monocrystalline silicon samples (intrinsic, boron-, phosphorus-, or arsenic-doped, float-zone or Czochralski-grown) between 6K and 800K by means of longitudinal field-quenching (LFQ) and radio-frequency mu(+) spin resonance (RF mu SR). The LFQ data can be described consistently by coupled equations of motion for the muonium spin systems if spin exchange processes as well as transitions between different muon states are taken into account. It is shown that the initial formation probabilities of the different muon states, the ionization rate of the anomalous muonium, and the electron spin exchange rates depend strongly on the charge carrier densities. These results are in agreement with the RF mu SR data obtained on the same samples if the different time scales of RF mu SR and LFQ experiments are taken into account. At temperatures above 300K both RF mu SR and longitudinal relaxation results appear to indicate reversible ionization of normal muonium.