d magnetism in the amorphous Y-Co, Y-Ni, and Y-Fe alloys

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Abstract
In this paper we describe the magnetic properties of Y-M amorphous alloys (M = Fe, Co, Ni) in which only 3d magnetism is involved. When the properties are not strongly dependent on environment effects, they are similar to those observed in the corresponding crystalline alloys: (i) Y-Co and Y-Ni alloys exhibit ferromagnetism when the 3d moment is large; (ii) far from the critical concentration for the disappearance of magnetism, the decrease of the 3d moment with increasing Y-concentration is similar in amorphous and crystalline alloys; (iii) near the critical concentration, very weak itinerant ferromagnetism may be observed in amorphous Y-Ni alloys as well as in the crystalline ones. On the contrary, the properties which are dependent on environment effects are strongly affected by the amorphous state: the properties of metamagnetism of itinerant electrons, which are very important in crystalline Y-Co alloys near the critical concentration, lead in the amorphous state to a persistence of a mean 3d moment at much higher concentrations due to the diversity of environments; Y-Fe alloys are spin-glasses due to competing positive and negative magnetic interactions which in R2Fe17 compounds lead to helimagnetic structures.