New multicomponent metallic liquids can be undercooled far below their melting points. On approaching the liquid to glass transition the increasing packing fraction of the atoms leads to a drastic slowing in their dynamics.
Neutron time-of-flight spectroscpopy allows the study of this so called cage effect on the relevant picosecond time scale and microscopic length scale and therefore is a profound test of the predictions by the mode coupling theory of the liquid to glass transition.
Ref.: Meyer A., Phys. Rev. B 66, 134205 (2002).