NEUTRON BRILLOUIN-SCATTERING IN A METALLIC-GLASS

The dispersion of collective modes in a metallic glass (Mg70Zn30) measured previously at the thermal neutron time-of-flight spectrometer, IN4, of the HFR of the ILL has been extended towards lower momentum transfers, down to the first pseudo-Brillouin zone, for the first time. This extension to momentum transfers not accessible up to now was possible using the high-resolution time-of-flight spectrometer, HET, at the new spallation source, ISIS. In the region of overlap, the two parts of the dispersion determined with different samples of the same metallic glass on different instruments agree very well. Also, the earlier discrepancies with the dispersion determined for this metallic glass from a computer simulation have been almost completely eliminated due to a more recent and more complete investigation.