Experimental evidence for a dynamical crossover in liquid aluminium

F Demmel, A Fraile, D Szubrin… - Journal of Physics …, 2015 - iopscience.iop.org
F Demmel, A Fraile, D Szubrin, WC Pilgrim, C Morkel
Journal of Physics: Condensed Matter, 2015iopscience.iop.org
The temperature dependence of the dynamic structure factor at next-neighbour distances
has been investigated for liquid aluminium. This correlation function is a sensitive parameter
for changes in the local environment and its Fourier transform was measured in a coherent
inelastic neutron scattering experiment. The zero frequency amplitude decreases in a
nonlinear way and indicates a change in dynamics around $1.4\cdot {{T} _ {\text {melting}}}
$. From that amplitude a generalized viscosity can be derived which is a measure of local …
Abstract
The temperature dependence of the dynamic structure factor at next-neighbour distances has been investigated for liquid aluminium. This correlation function is a sensitive parameter for changes in the local environment and its Fourier transform was measured in a coherent inelastic neutron scattering experiment. The zero frequency amplitude decreases in a nonlinear way and indicates a change in dynamics around . From that amplitude a generalized viscosity can be derived which is a measure of local stress correlations on next-neighbour distances. The derived generalized longitudinal viscosity shows a changing slope at the same temperature range. At this temperature the freezing out of degrees of freedom for structural relaxation upon cooling sets in which can be understood as a precursor towards the solid state. That crossover in dynamics of liquid aluminium shows the same signatures as previously observed in liquid rubidium and lead, indicating an universal character.
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