Abstract
First-order reversal curves (FORC) and the FORC distribution provide a detailed characterization of the relative proportions of reversible and irreversible components of the magnetization of a material, revealing the dominant interactions in the system. Alloys with the nominal composition SmFe2 were obtained by melt-spinning with a cooper wheel velocity of 30 m/s. X-ray powder diffraction analysis showed a greater part consisting of an amorphous phase and a very small amount of SmFe2 crystalline phase with an average crystallite size of 8 nm. A constant acceleration Mössbauer spectrum, measured at room temperature in transmission mode, was fitted to a continuous distribution of effective fields at the nucleus of the amorphous phase (about 84% of the total area), plus two sextets for the non-equivalent sites of Fe in the SmFe2 crystalline phase. 91 first-order reversal curves were collected in a Quantum Design PPMS-VSM with reversal fields from –800 mT to +800 mT and using a calibration field of 850 mT. The obtained FORC diagrams showed a combined effect of a local interaction field and a mean interaction field, and showed that the reversible magnetization is a function of both, the applied magnetic field and the irreversible magnetization.
Highlights
Rare earth-Fe2 alloys are of great interest due to their high magnetostriction even at low magnetic fields [1]
There has been an increasing interest in the application of the so-called first order reversal curves (FORC) for the analysis of magnetic hysteresis [4,5]; this approach is not model-based and the system under study is described by the FORC distribution which is directly obtained from first order reversal curves measurements
First order reversal curves were used for the analysis of magnetic hysteresis in SmFe2 melt
Summary
Rare earth-Fe2 alloys are of great interest due to their high magnetostriction even at low magnetic fields [1]. A model where the FORC distribution, ρ(Bc , Bb ), is equal to the Preisach distribution in its moving variation model [11,12,13] was used for the interpretation of the SmFe2 FORC diagrams. This does not imply that the Preisach model describes the behavior of the interactions present in our study sample, but it is going to be used as a comparative foundation
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