A Study of Concentrated Metallic Spin-Glasses from a Viewpoint of Itinerant Electron Magnetism

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Macroscopic magnetic properties and magnetic phase diagrams of concentrated spin-glasses show rather universal characteristics among many materials including metallic and insulating, crystalline and amorphous solids. However, there are marked differences among materials in the temperature variation behavior of the spin-wave stiffness constant and the spin-wave intensity. In order to clarify the nature of each magnetic phase and phase transition properties and especially to make clear the origin of the wide variety in spin dynamical properties, we made elastic and inelastic neutron scattering experiments of a pseudo-binary alloy Fe_<65>(Ni_<0.866>Mn_<0.134>)_<35>. We also made an elastic neutron scattering experiment on Cu_2(Mn_<0.70>Ti_<0.30>)Al. The former can be classified as an itinerant electron magnet. The latter is a typical member of localized moment magnets. For both systems, magnetic diffuse scattering intensity increases as the system is cooled toward the spin-glass freezing temperature even in the ferromagnetic phase. However, the magnetic correlation length in the Fe_<65>(Ni_<0.866>Mn_<0.134>)_<35> is considerably larger than that in the Cu_2(Mn_<0.70>Ti_<0.30>)Al. In the Fe_<65>(Ni_<0.866>Mn_<0.134>)_<35>, spin-wave excitations have been observed in the spin-glass phase as well as in the ferromagnetic phase. Spin-wave stiffness constant does not change appreciably at the spin-glass freezing temperature.