TEMPERATURE-DEPENDENT NMR FEATURES OF THE AL65CU20RU15 ICOSAHEDRAL ALLOY

The Al65Cu20Ru15 icosahedral alloy was studied by Al-27 nuclear magnet ic resonance from 150 to 1110 K. The Knight shift of the unresolved re sonance line was observed to significantly increase above 500 K. This uncommon temperature dependence of the Knight shift is interpreted in terms of the presence of a pseudogap at the Fermi level. The spin-latt ice relaxation rate deviates from the linear temperature dependence of Korringa relaxation below 500 K, and above 500 K it is dominated by a thermally activated process with a small activation energy of 0.48 eV . This energy is distinctly different from the activation energy obser ved in simple metallic alloys.