Search

Alfv\'en-wave resonances are used to measure time decay of the electron-hole drop radius in stressed Ge, and striking new properties of the condensate are observed. Compared to standard results, the drop volume is larger by more than 1000, and the drop lifetime is increased from 40 \ensuremath{\mu}sec to over 400 \ensuremath{\mu}sec. We believe the long-lived condensate corresponds to low-density Ge $〈111〉$ or Ge $〈110〉$ phases with one or two electron ellipsoids occupied.

A summary of the likely relaxation process of the magnetic moment component parallel to the static magnetic field in yttrium iron garnet at 2 to 30 deg K is given. The relaxation rate of the S modes for Raman processes in which, by magnetic dipolar coupling between an S mode and a thermal spin wave, the Z component of the magnetic moment changes by plus or minus 2 mu /sub B/. Through calculations, it is shown that M/sub z/ is expected to relax by magnetic dipole interaction with thermal spin waves at a rate comparable with observation. (C.J.G.)