Magnetic properties of icosahedral Al-Mo-Fe and Al-Ta-Fe alloys.

Abstract

Single-phase icosahedral quasicrystals of the composition ${\mathrm{Al}}_{80}$${\mathrm{Mo}}_{9}$${\mathrm{Fe}}_{11}$ and ${\mathrm{Al}}_{70}$${\mathrm{Ta}}_{10}$${\mathrm{Fe}}_{20}$ have been prepared by rapid quenching from the melt. X-ray-diffraction measurements have yielded quasilattice constants of 4.600\ifmmode\pm\else\textpm\fi{}0.003 A\r{} for both alloys. Room-temperature $^{57}\mathrm{Fe}$ M\"ossbauer-effect measurements show a nearly symmetric doublet in Al-Mo-Fe and an asymmetric doublet in Al-Ta-Fe. These results are analyzed in terms of various distributions of Fe quadrupole splittings. Magnetization measurements for both alloys show a magnetization that exhibits Curie paramagnetism at low temperatures (T\ensuremath{\lesssim}100 K) and Pauli paramagnetism at higher temperatures. These results show a localized Fe moment of 0.19${\ensuremath{\mu}}_{B}$ in Al-Mo-Fe and 0.48${\ensuremath{\mu}}_{B}$ in Al-Ta-Fe.