Muonium states in germanium

Abstract

An anomalous muonium state similar to that in silicon has been found in germanium. This state can be described an anisotropic hyperfine interaction with the parameters $\frac{{A}_{\ensuremath{\perp}}}{h}=130.7\ifmmode\pm\else\textpm\fi{}1$ MHz and $\frac{{A}_{\ensuremath{\parallel}}}{h}=26.8\ifmmode\pm\else\textpm\fi{}1$ MHz. In contrast to Si this anomalous muonium state in Ge was not observed at low external fields. In addition, a detailed investigation of normal muonium in Ge was carried out. For undoped Ge the hyperfine constant is found to be temperature independent in the range between 6 and 81 K with an average value of $\frac{A(\mathrm{Ge})}{h}=2361\ifmmode\pm\else\textpm\fi{}3$ MHz or $\frac{A(\mathrm{Ge})}{A(\mathrm{vac})}=0.5290\ifmmode\pm\else\textpm\fi{}0.0007$. The present value is considerably lower than that published by Gurevich et al. The relaxation rate of normal muonium in the Ge sample investigated increases sharply above about 50 K with an activation energy of 14 meV. A correlation with the thermal activation of impurity charge carriers is suggested.