Role of diffused Co atoms in improving effective exchange coupling inSm−Co∕Fespring magnets

Abstract

In Sm-Co/ Fe exchange-spring magnet films, the magnetization reversal processes of constituent elements and layers were studied with an emphasis on the role of diffused Co atoms. Enhanced coupling effectiveness was observed in a film with a graded interface where significant Co diffusion into the Fe layer was observed by means of electron microscopy. Comprehensive insight into the magnetization reversal processes was obtained by combining micromagnetic simulation with element-and depth-resolved x-ray resonant magnetic scattering. The approach unambiguously identifies distinctive composition profiles across the graded interface and provides the magnetization behavior of the diffused Co.

Noncollinear Fe spin structure in (Sm-Co)/Fe exchange-spring bilayers: Layer-resolved57Fe Mössbauer spectroscopy and electronic structure calculations

“…In Fig. 7 (b), the R 23 dependence of the interface (1-10 ML) and near-interface (15)(16)(17)(18)(19)(20)(21)(22)(23)(24) probe layers still exhibits a monotonic drop, but one can expect formation of a R 23 minimum even in the case of H int = ∞ for severe 57 Fe -56 Fe intermixing.…”

“…2. This means that less controllable variations of the sample properties during their preparation (e.g., changes in the exchange coupling between the hard and soft layer due to interdiffusion and /or changes in the local magnetic anisotropy due to compositional variations at the hard / soft interface caused by interdiffusion [17]) affect the switching of the Sm-Co layer. On the other hand, for the fitting of the spectra of sample E (surface) a very weak subspectrum with a hyperfine field distribution P(H hf ) and with a relative spectral area (relative integrated spectral intensity) of only 4 -6 % had to be added as a small correction to the dominant sharp α-Fe sextet …”

“…(4) and (5) The standard theoretical approach for the description of the magnetization reversal process is based on the micromagnetic modeling of the system using a one-dimensional continuum model or a discrete chain model [6,9,17,22,23,32,34]. These models provide a good intuitive picture of the magnetization reversal process and are very useful for a qualitative understanding of the magnetic behavior.…”

Fabrication of bulk nanocomposite magnets via severe plastic deformation and warm compaction

“…The reason for this improvement can be attributed to the recent finding that interphase exchange coupling favors interdiffused interfaces ͑graded interface͒. 22,23 To characterize the elemental composition in the bulk nanocomposite magnets, three-dimensional ͑3D͒ atom probe analysis has been conducted for a SmCo 5 + 20 wt % Fe nanocomposite bulk magnet. A 3D atom map of Sm and Fe is shown in Fig.…”

Reversal of patterned Co/Pd multilayers with graded magnetic anisotropy

“…3,4 Experimentally, synthesis of graded anisotropy materials, as well as the ability to characterize the anisotropy gradient have been demonstrated, typically in thin films. 5,6 The full-film geometry is integral to the magnetization reversal process, and often makes it nontrivial to compare with the graded anisotropy models based on isolated grains. 3,4,7 For example, in Co/Pt and Co/Pd multilayers the reversal is dominated by domain nucleation and subsequent propagation laterally along the plane of the film, which convolutes the interpretation of essential parameters such as intrinsic anisotropy and switching field distribution (SFD).…”