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The structural and magnetic properties of the evaporated Fe/V multilayers with a fixed V-layer thickness (tV = 1.5 nm) and variable Fe layer thicknesses (0.75 nm < or = tFe < or = 6 nm) have been studied by X-ray reflectivity and high-angle X-ray diffraction, conversion-electron Mössbauer spectrometry, and vibrating sample magnetometry. The results show that multilayers are formed with a broad Fe/V interface and pure crystalline bcc-Fe layers in the center of the individual subsystems. The Fe spin orientation is aligned in the film plane in the individual centers as well in the interfacial regions. The interfacial anisotropy constant Ks was estimated to be equal to 0.04 mJ/m2. This parallel magnetic anisotropy is discussed in terms of reduced symmetry effects on the hybridized 3d states.

Sputtered (TbCo2.5 25 nm/Fe 20 nm) multilayers have been analyzed by laser-assisted tomographic atom probe. It allowed us to perform three-dimensional reconstructions of the layers and to determine their composition at the atomic scale. From the concentration profiles inside the multilayer, we show that the diffused interfaces are not symmetric and that a stronger Fe-Co mixing is present at the top of the crystalline iron layers as compared to the top of amorphous TbCo layers. [ABSTRACT FROM AUTHOR]

In nanometric Tb/Fe multilayers, the effect of the electronic energy loss of fast heavy ions on the interfaces has been selectively investigated by 57Fe conversion electron Mössbauer spectrometry, thanks to deposition of 57Fe probe layers at the bottom or top of the natural iron layers. The as-deposited Tb-on-Fe interfaces are sharp while the Fe-on-Tb ones are amorphous and diffuse. Modifications of the environments of the 57Fe probe atoms were investigated as a function of the electronic stopping power (Sn and U ions) and the ion fluence. An effect of recrystallization of iron is evidenced at the initially diffuse Fe-on-Tb interface while only mixing between Fe and Tb atoms is observed at the sharp Tb-on-Fe interface. For very high rates of electronic energy deposition (stopping power ∼60 keV/nm), severe mixing leads to the interdiffusion of the layers. [ABSTRACT FROM AUTHOR]

The Fe spin structure in ultrahigh-vacuum-deposited hcp Tb(t[sub Tb])/bcc Fe(t[sub Fe]) multilayers (t[sub Tb] and t[sub Fe] are the Tb and Fe layer thicknesses respectively) with perpendicular magnetic anisotropy (PMA) and large coercivity at low temperatures was investigated by [sup 57]Fe Mossbauer spectroscopy, the polar magneto-optical Kerr effect, and superconducting quantum interference device magnetometry. A spontaneous reversible temperature-driven Fe spin reorientation transition from orientation parallel to the film plane to an out-of plane orientation (with Fe spins tilted by an angle relative to the film normal direction) was observed upon cooling below the reorientation temperature T[sub R]. At a fixed value of t[sub Tb], T[sub R] was found to follow a t[sub Fe][sup -1] behaviour, indicating that the PMA originates from the interfaces. Upon cooling, the perpendicular remanent magnetization shows a step-like increase near the magnetic ordering temperature of Tb, contrary to (T), which exhibits no such anomaly. Apparently, strong coupling of Fe layers via magnetic Tb layers affects the perpendicular magnetic domain structure at remanence. Further, [sup 57]Fe probe layer Mossbauer results concerning structure, composition and Fe spin orientation within Fe-on-Tb and Tb-on-Fe interfaces are reported. [ABSTRACT FROM AUTHOR]

Abstract: Iron and chromium powder mixtures were elaborated by mechanical alloying (MA) from 0 to 30h of milling times and over the whole concentration range. Mössbauer spectrometry was performed in order to characterize the influence of the nanostructure on magnetic properties, especially of the intergranular zone. Mössbauer results at 300K show that the properties of MA FeCr powders alloying over the whole concentration range can be interpreted taking into account two contributions: a contribution associated with the FeCr nanograin core, which is very close to the FeCr bulk alloy with the same composition and contribution associated with the weakly magnetic disordered intergranular zone, created by gases dissolved during milling. [Copyright &y& Elsevier]