Pressure effect on the magnetic properties of amorphous alloys composed of icosahedral clusters

Abstract

The pressure effects on the magnetic properties have been investigated for amorphous alloys prepared by high-rate DC sputtering. The pressure derivatives of magnetization and the Curie temperature are significantly large. The concentration dependences of and are similar to those of various magnetovolume and magnetoelastic properties such as the spontaneous volume magnetostriction , forced volume magnetostriction and compressibility . The pressure derivative of the Curie temperature is also large, and the linear relation of versus plot is accounted for by taking inhomogeneity into consideration. The linear plot of versus is explained in terms of spin fluctuations. In connection with the peculiar amorphous structure composed of icosahedral clusters, both and are different from those of amorphous Fe-based binary alloys. The value of determined from the pressure dependence of the spin-wave stiffness constant D is reasonable. The spin freezing temperature is increased with increasing pressure, consistent with the theory concerned with itinerant electron spin-glass systems.

Neutron diffraction study of LaFe11.31Si1.69 and LaFe11.31Si1.69H1.45 compounds

“…According to the analyses initiated by Fukamichi et al on glassy La(Fe x Al 1−x ) 13 [29] and latter on crystallized parent compounds [4][5][6][7][8][9][10]12,13], the icosahedral-type arrangement of Fe atoms typically encountered in the Fe-rich La(Fe x X 1−x ) 13 quite well fulfil the conditions for the magnetic depolarisation of metal Fe as observed for the ␣-Fe to ␥-Fe, in which the later iron is closely packed. To the larger atom volume configuration (V FeII > V FeI ) corresponds the larger magnetic Fe-moment FeII (2.2 B ) > FeI (1.42 B ), the CN24 (coordination number) of the later site sharing even shorter FeI-FeII distances than that of the reference ␣-Fe.…”

“…see Ref. [29]. Consequently above T C , the long range magnetic ordering of the FeII sublattice vanishes definitively.…”