Compelling evidence for band-type conductivity and even bulk
superconductivity below T_c≈8 K has been found in
69,71Ga-NMR experiments in crystalline ordered, giant Ga_84
cluster-compounds. This material appears to represent the first realization of
a theoretical model proposed by Friedel in 1992 for superconductivity in
ordered arrays of weakly coupled, identical metal nanoparticles.Comment: 5 pages, 4 figure