Magnetism in an Amorphous Fe-Pd-P Alloy System

Citation

Sharon, Thomas Edward (1971) Magnetism in an Amorphous Fe-Pd-P Alloy System. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/SKE6-7667. https://resolver.caltech.edu/CaltechTHESIS:04122018-091817826

Abstract

Amorphous alloys of composition Fe_xPd_80-xP₂₀ (13 ≤ x ≤ 44) have been prepared by rapid quenching from the liquid state. The Mössbauer effect in Fe⁵⁷ has been used to study the magnetic properties of these materials. The hyperfine field distributions have been determined from these experiments, as a function of composition and temperature. The results indicate that the electronic state of Fe in these alloys remains essentially constant throughout the composition range, and that the Pd d band is filled by electron transfer from phosphorus.

The variation of the magnetic transition temperature with composition has been determined by combining the Mössbauer effect results with complementary magnetic measurements. There is a sharp change in the slope in this curve at x ≃ 26. Below this concentration, the long range magnetic order which prevails in the higher Fe concentration alloys has broken down, giving rise to a more local ordering.

The Mössbauer effect results confirm the existence of weakly coupled Fe atoms in all the amorphous Fe-Pd-P alloys. These atoms reside in low effective fields, and can participate in the spin-flip scattering process which produces a Kondo effect (resistivity minimum). The large critical concentration observed is also an indication that the spin correlations are greatly reduced in these amorphous alloys.

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