Dynamical properties of ordered Fe–Pt alloys

• Published in: Journal of alloys and compounds Vol. 651; pp. 528 - 536
• Main Authors: Sternik, M., Couet, S., Łażewski, J., Jochym, P.T., Parlinski, K., Vantomme, A., Temst, K., Piekarz, P.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 05.12.2015
• Subjects: Alloys; Density of states; Dispersion; Ferrous alloys; First principle calculations; Inelastic neutron scattering; Intermetallic compounds; Iron compounds; Mathematical analysis; Ordered Fe–Pt alloys; Phase transitions; Phonons; Softening; Titanium base alloys; First principle calculations; Phase transitions; Ordered Fe–Pt alloys; Inelastic neutron scattering; Phonons
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2015.08.097

The structure, magnetic properties, and lattice dynamics of ordered Fe–Pt alloys with three stoichiometric compositions, Fe3Pt, FePt and FePt3, have been investigated using the density functional theory. Additionally, the existing experimental data have been complemented by new measurements of the Fe projected phonon density of states performed for the Fe3Pt and FePt3 thin films using the nuclear inelastic scattering technique. The calculated phonon dispersion relations and phonon density of states have been compared with the experimental data. The dispersion curves are very well reproduced by the calculations, although, the softening of the transversal acoustic mode TA1 leads to some discrepancy between the theory and experiment in Fe3Pt. A very good agreement between the measured spectra and calculations performed for the tetragonal structure derived from the soft mode may signal that the tetragonal phase with the space group P4/mbm plays an important role in the martensitic transformation observed in Fe3Pt. For FePt3, the antiferromagnetic order appearing with decreasing temperature has been also investigated. The studies showed that the phonon density of states of FePt3 very weakly depends on the magnetic configuration. •Within the same ab initio formalism Fe3Pt, FePt, FePt3 alloys are studied.•The obtained results are confronted with the previous and new experimental data.•The anisotropy of the partial Fe and Pt phonon DOS is observed in Fe–Pt alloys.•The important role of soft mode in the transformation of Fe3Pt is shown.•None of the antiferromagnetic structures is energetically favored in FePt3.