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What happens if you embed clusters of a noble metal into
another noble metal, Ag in Au, say. Presumably something boring.
Both these metals have weak Coulomb and electron-phonon (EP)
coupling so you will probably end up with a somewhat disordered
weak coupling metal. You actually find an enhancement of the
electron-phonon coupling by a factor of 40(!), inferred from the T
linear resistivity. This is larger than the coupling in Pb which is
among the traditional higher temperature superconductors.
Uncovering what is going on requires a combination of ab initio
calculations and many body theory. In the absence of detailed ab
initio results I will suggest a spatially inhomogeneous model
motivated by the experiments, distinguishing "bulk" from
"interface" in these materials, and discuss what emerges in
terms of transport. If EP coupling is indeed so large what about
superconductivity? I will comment on why that hope is belied. |