POLARIZED NEUTRON-SCATTERING STUDY OF BETA-MN AND BETA-MN0.9AL0.1

Polarized neutron scattering measurements have been performed on beta-Mn and beta-Mn0.9Al0.1 to study spin fluctuations. A large magnetic scattering peak at around Q = 1.5 angstrom-1 was observed in the spectra obtained in the quasi-elastic condition, indicating the existence of strong spin fluctuations with antiferromagnetic correlation. The energy and Q spectra at 290 K exhibit nearly the same profiles and intensity for both samples. However, the energy spectra at low temperatures are quite different. For the pure beta-Mn, the intensity decreases with decreasing temperature and the energy width remains as broad as at 290 K. For beta-Mn0.9Al0.1, on the other hand, the intensity increases due to narrowing of the energy spectrum at low temperatures, implying a slowing down of spin fluctuations. These results are discussed in terms of a spin-liquid to spin-glass transition caused by Al substitution.