THE DISTINCTION BETWEEN THE MAGNETIC-PROPERTIES OF QUASI-CRYSTALLINE AND AMORPHOUS AL85-XPD15MNX ALLOYS

Quasicrystalline and amorphous Al85-xPd15Mnx (x = 12, 13, 14 and 15) a lloys have been prepared by rapid melt quenching and high-rate Dc sput tering. The saturation magnetic moment M(s), the magnetic Mn atom rati o, the magnetic moment per magnetic Mn atom P-c and spin glass behavio ur have been investigated for both these phases. The temperature depen dence of DC magnetic susceptibility for these quasicrystalline and amo rphous alloys follows a Curie-Weiss law over a wide temperature range. The value of M, and the average magnetic moment per Mn atom (P-c) for the quasicrystalline alloys are much smaller than those for the amorp hous alloys. The magnetic Mn atom ratio in the quasicrystalline phase is about 10%, being almost half that in the amorphous phase in a simil ar manner to the Al80-xCu20Mnx (x = 13, 14 and 15) alloy system. The M n concentration dependence of P-c in the quasicrystalline phase is ste eper than that in the amorphous phase, and the value of P-c of the qua sicrystalline Al70Pd15Mn15 alloy exceeds 5(mu B) of a bare moment of M n. It is, therefore, considered that a giant moment is formed by polar ization of 4d electrons of Pd in the quasicrystalline alloy. The prese nt alloys in both phases are magnetically dilute alloys and spin glass behaviour has been observed. The spin freezing temperature T-f for th e quasicrystalline phase is lower than those for the amorphous phase i n accordance with the smaller Mn atom ratio. From these results, a mar ked difference in the magnetic properties between the quasicrystalline and amorphous phases has been confirmed, reflecting their different l ocal atomic structure.