The unusual magnetism of manganese atoms in an icosahedral Al 72.4 Pd 20.5 Mn 7.1 single-grain quasicrystal was studied by 27 Al nuclear magnetic resonance ͑NMR͒, magnetic susceptibility, and electrical resistivity measurements. Between room temperature and 50 K both the 27 Al NMR linewidth and the frequency shift exhibit a Curie-Weiss-type, 1/(TϪ) temperature dependence. At lower temperatures a significant narrowing of the linewidth, concomitant with a reduction of the frequency shift is

more »

... ed. These features can be explained by a gradual reduction of the local exchange magnetic field at the position of the 27 Al nuclei that is transferred from the manganese d moments via the conduction electrons. Two possible origins of this phenomenon are discussed: ͑i͒ the Kondo-like screening of manganese moments by the conduction electrons and ͑ii͒ the "resistivity"-damping of the RKKY interaction due to increasing electron localization at low temperatures.