Origin of magnetic moments in i-Al–Pd–Mn quasicrystal

Abstract

Abstract Using ab-initio density-functional methods in the generalized gradient approximation we have investigated the origin of magnetic moments on Mn atoms in icosahedral (i) Al–Pd–Mn quasicrystals. Two major mechanisms contribute to the formation of magnetic moments on Mn atoms located at special sites – loosely packed environments of the Mn atoms and the interaction of the Mn atoms with nearest-neighbor Pd atoms leading to a shift of the Mn d-band to lower binding energies and an increased partial density of states at the Fermi level. Mn–Pd nearest neighbors exist only at special sites located at intersections of the pseudo-Mackay and the Bergman clusters building the icosahedral structure. A change in the chemical decoration of these sites can lead to a complete disappearance of magnetism in i-Al–Pd–Mn. Total energy calculations show that the models with a chemical ordering disfavoring moment formation on Mn atoms are also lowest in energy.