Hyperfine Spectroscopy and Characterization of Muonium Centers in ZnGeP$_{2}$

We have recently initiated a study of the defect states formed when positive muons are implanted into chalcopyrite structured II-IV-V$_{2}$ compounds to extend our investigation of the muonium defect centers as an experimentally accessible analog of isolated hydrogen defect states in semiconductors. In this presentation, I will discuss one of the initial observations of neutral muonium defect centers in ZnGeP$_{2}$; specifically, the hyperfine characterization of the neutral muonium centers observed in ZnGeP$_{2}$ using the Muon Spin Relaxation technique (MuSR). The spin precession frequencies in a field of 4.0 Tesla yield a zero-temperature hyperfine constant of $\sim $1962 MHz for the promptly formed Mu$^{0}$ state. Subsequently, we performed T$_{1}^{-1}$ longitudinal depolarization measurements in low magnetic fields. Decoupling curves show a different anisotropic Mu$^{0}$ with A$_{2}$=3185 MHz and D=374 MHz, where the D is the dipolar contribution. I will report on the spectroscopic hyperfine characterization of the neutral muonium centers observed in ZnGeP$_{2}$.