Ab initio calculations of magnetic structure and lattice dynamics of Fe/Pt multilayers

Abstract

Abstract. The magnetization distribution, its energetic characterization by the interlayer coupling constants and lattice dynamics of (001)-oriented Fe/Pt multilayers are investigated using density functional theory combined with the direct method to determine phonon frequencies. It is found that ferromagnetic order between consecutive Fe layers is favoured, with the enhanced magnetic moments at the interface. The bilinear and biquadratic coupling coefficients between Fe layers are shown to saturate fast with increasing thickness of nonmagnetic Pt layers which separate them. The phonon calculations demonstrate a rather strong dependence of partial iron phonon densities of states on the actual position of Fe monolayer in the multilayer structure.

Dynamics and stability of icosahedral Fe–Pt nanoparticles

“…This means that, contrary to platinum shells, the inter-atomic distances in both iron shells, the surface one of Fe 43 Pt 12 and subsurface of Fe 12 Pt 43 , are strongly stretched (∼ 8 − 10%) which can be one of the main reasons of the ironterminated NP instability. The similar influence of strain on iron surface stability was observed previously in the Fe monolayer on W(110) surface 44 and in FeAu and FePt multilayers 45,46 . In both particles, the NN distances between the Fe and Pt atoms located in the first and second shell (∼ 2.50Å) and between the central atom and the first shell (∼ 2.60Å) are reduced comparing to the Fe-Pt distance in the bulk fct L1 0 structure (2.70Å).…”

“…A similar influence of strain on iron surface stability was observed previously in the Fe monolayer on the W(110) surface 44 and in FeAu and FePt multilayers. 45,46 In both particles, the NN distances between the Fe and Pt atoms located in the first and second shell (B2.50 Å) and between the central atom and the first shell (B2.60 Å) are reduced compared to the Fe-Pt distance in the bulk fct L1 0 structure (2.70 Å). 47 It causes the internal stress in the core, which may be the driving force for Fig.…”

Dynamical properties of ordered Fe–Pt alloys

“…The latter technique provides information on the Fe contribution to the phonon density of states (PDOS), and it has been applied to ordered and disorder polycrystalline Fe-Pt alloys, 11,12 thin films, 15 as well as to nanoclusters 13,14 . The theoretical studies based on ab initio methods enabled calculation of the phonon dispersion relations of Fe/Pt multilayers 16 , estimation of the magnetic anisotropy of Fe/Pt(001) and Pt/Fe/Pt(001) systems 17 , identification of the structural and magnetic phases in FePt surface alloys 18 , determination of the partial Fe PDOS in ordered FePt 15 and investigation of the soft mode behavior in Fe 3 Pt. 19 For FePt, the first-principles results were compared with the partial Fe PDOS measured by the NIS method.…”