  To experimentally clarify the changes in structural and dynamic
heterogeneities in a metallic glass (MG), Gd65Co35, by rejuvenation with a
temperature cycling (cryogenic rejuvenation), high-energy x-ray diffraction
(HEXRD), anomalous x-ray scattering (AXS), and inelastic x-ray scattering (IXS)
experiments were carried out. By a repeated temperature change between liquid
N2 and room temperatures 40 times, tiny but clear structural changes are
observed by HEXRD even in the first neighboring range. Partial structural
information obtained by AXS reveals that slight movements of the Gd and Co
atoms occur in the first- and second-neighboring shells around the central Gd
atom. The concentration inhomogeneity in the nm size drastically increases for
the Gd atoms by the temperature cycling, while the other heterogeneities are
negligible. A distinct change was detected in a microscopic elastic property by
IXS: The width of longitudinal acoustic excitation broadens by about 20%,
indicating an increase of the elastic heterogeneity of this MG by the thermal
treatments. These static and dynamic results explicitly clarify the features of
the cryogenic rejuvenation effect experimentally.
