Low-temperature magnetic properties of Al-Pd-Mn-B quasicrystalline alloys

Low-temperature magnetic properties of the Al70-xPd15Mn15Bx icosahedral alloys (0 less than or equal to x less than or equal to 6) were measured by a superconducting quantum interference device (SQUID). The alloy with x = 0 is a simple spin glass: the thermoremanent magnetization, M-R(t), is characterized by a stretched exponential: M-R(t) = M-1 + M-0 exp[-(t/tau)(beta)]. The alloy with x = 1 is a cluster glass: M-R(t) is also in the stretched exponential form, while the alloy with x = 1.5 is superparamagnetic. In alloys with x = 1 and 1.5, there is a very small amount of a ferromagnetic component. The alloys with 2.5 less than or equal to x less than or equal to 6 are composed of a ferromagnetic component and a superparamagnetic and/or Curie-Weiss paramagnetic one. Therefore, the addition of B significantly changes the magnetic state of the Al-Pd-Mn alloys, owing to the formation and growth of magnetic Mn clusters. (C) 1998 Elsevier Science B.V. All rights reserved.