Stokes–Einstein relation in dense metallic glass-forming melts

Quasielastic neutron scattering has been used to investigate atomic motion in a very fragile binary metallic melt and a multicomponent bulk glass-forming metallic melt. Both melts show a breakdown of the Stokes–Einstein relation and display a change in the slope of $InD$ dependence on $In(η/T)$⁠. We also observed that the values for the exponent in the fractional Stokes–Einstein relation are not in the commonly observed range for $Cu46Zr42Al7Y5$ melts. At low temperatures, the deviation from the Stokes–Einstein law is very significant and can be expressed in the form of a power law with exponent $ξ=−1.82±0.08$⁠. The change in the slope is found to be associated with a change in friction coefficient while increasing the packing density of the melt. The abrupt change in the value of friction coefficient is independent of packing density, but it occurs at a common value of $ζ=(3.2±0.1)×10−12kgs−1$ in these melts.