Anomalous muonium in germanium

Abstract

In semiconductors like Si and Ge, so-called normal Muonium Mu with an isotropic hyperfine interaction is well kno%m 11,2 I. In addition an anomalous muonium state Mu e was found in Si 111 and was investigated in detail in ref. 131. A Hamiltonian with an anisotropic hyperfine interaction was used to describe the data. In Ge this state had not been discovered as yet. Using the high muon flux at SIN, we made pSR measurements on undoped (p<50 ~cm) Ge single crystals in strong transversal magnetic fields with high statistics. The Ge targets were cooled to 10 K. Fig.1 shows the Fourier transform of a run with an external field of 4.5 kG parallel to the 110OI-direction. The peak at 50.5 MHz is due to the cyclotron frequency at SIN. The frequency at 61MHz is the "free" p+ component in a diamagnetic environment. Additionally there are significant peaks at 31MHz and 112 MHz, which can be attributed to an anomalous muonium state Mu~