MUON LEVEL-CROSSING RESONANCE IN SIAL

MuLCR spectra from single-crystal Si:Al have been taken at 30 K with t he field along the [111] direction. The spectra show strong resonances near 12 and 50 mT, and weaker resonances near 38 and 42 mT. There is also indication of lines near 15 and 21 mT. The strong signals are due to the well-known zero crossings for Mu in Si, and the weak signals may be associated with the quadrupole interaction of Al-27, as predict ed by ab initio electronic structure calculations.