Changes in the spin-glass state and the atomic structure on annealing the amorphous Y - Fe alloys

Abstract

Annealed amorphous alloys have been investigated by means of AC magnetic susceptibility measurement and x-ray diffraction analysis. The amorphous (x = 15, 16, 20, 25 and 30) alloys annealed at 523 K for 180 min exhibit re-entrant spin-glass behaviour, while a direct transition from a paramagnetic to a spin-glass phase occurs in the amorphous alloys with x = 7.5, 10 and 33.3. For the amorphous alloy, the Curie temperature and the magnetic moment increase, but the spin freezing temperature decreases on annealing. The magnetic phase diagram for the amorphous Y - Fe alloy system in the annealed state is similar to that for many other amorphous Fe-based alloy systems in the as-prepared state. Increases in the atomic distance of Fe - Fe pairs and in the coordination number of the nearest-neighbour Fe atoms on annealing have been observed. These structural changes explain the changes in the magnetic properties for annealed amorphous alloys.

Exchange interactions in hydrogen-induced amorphous YFe2

“…The estimated J values of HIA YFe 2 H x are 4.7 · 10 À22 J for x = 1.8, 11.2 · 10 À22 J for x = 3.0 and 14.1 · 10 À22 J for x = 3.4. In these estimates we assumed a coordination number of 8 for our HIA YFe 2 H x alloys as a report on vapor-quenched Fe-Y alloys [5] showed that the coordination numbers for Fe in amorphous Fe-Y alloys are around 8. Hence, the absolute values of J in our estimates may contain a systematic error due to the uncertainty of the coordination number.…”

“…Amorphous Fe-Y alloys have been studied extensively [3][4][5] due to their peculiar magnetic behavior which includes both paramagnetic to spin-glass transitions and large magnetovolume effects. Amorphous YFe 2 prepared by conventional vapor-quenching is known to show a paramagnetic to spin-glass transition at around 50 K [3].…”

Mössbauer spectroscopical investigation of amorphous Fe–Y alloy ribbons prepared by melt spinning

“…The magnetic properties of amorphous (a-) Fe-Y alloys are well investigated [6][7][8][9][10][11]. The magnetic order in Fe-rich a-Fe-Y alloys is ferromagnetic and of spin-glass type at low temperatures [12]. Although the magnetic properties of a-Fe-Y alloys are well investigated, the study of the vibrational dynamics of amorphous Fe-Y alloys are rare.…”