Mn magnetism in icosahedral quasicrystalline Al72.4Pd20.5Mn7.1 - art. no. 024203

The unusual magnetism of manganese atoms in an icosahedral Al72.4Pd20.5Mn7. 1 single-grain quasicrystal was studied by Al-27 nuclear magnetic resonance (NMR), magnetic susceptibility, and electrical resistivity measurements. B etween room temperature and 50 K both the Al-27 NMR linewidth and the frequ ency shift exhibit a Curie-Weiss-type, 1/(T-theta) temperature dependence. At lower temperatures a significant narrowing of the linewidth, concomitant with a reduction of the frequency shift is observed. These features can be explained by a gradual reduction of the local exchange magnetic field at t he position of the Al-27 nuclei that is transferred from the manganese d mo ments via the conduction electrons. Two possible origins of this phenomenon are discussed: (i) the Kondo-like screening of manganese moments by the co nduction electrons and (ii) the ''resistivity'' -damping of the RKKY intera ction due to increasing electron localization at low temperatures.