Origin of magnetism in crystalline and quasicrystalline AlMn and AlPdMn phases

The existence of localized moments on a small fraction of the Mn atoms in the $\mu -{\mathrm{Al}}_4{\mathrm{Mn}}_x{\mathrm{Cr}}_{1-x}$ hexagonal phase, closely related to AlMn quasicrystals, is shown by magnetization and nuclear magnetic resonance studies. Deviations from a Curie behavior observed in the μ phase, as well as in the AlMn, AlMnSi, and AlPdMn quasicrystals, can be interpreted by a Kondo effect. The crystallographic site leading to magnetic Mn in the μ phase is identified and the moment formation is justified by theoretical calculations. These results shed light on the origin of magnetism in quasicrystalline phases where a similar site must also exist.