Magnetic and Mössbauer study of Fe/Si multilayers

Abstract

The magnetic and structural properties of Fe/Si multilayers (Mls) have been studied by x-ray diffraction (XRD) and conversion electron Mössbauer spectroscopy (CEMS) methods. Strong antiferromagnetic (AF) coupling J=−1.93 mJ/m2 accompanied by saturation field of 1.5 T has been found for Si layer thickness dSi=1.4 nm. Magnetic moment measurements of Fe/Si Mls vs Fe thickness revealed that 0.25 nm of Fe per single interface is magnetically inactive. The CEMS spectra recorded at room temperature consist of the Zeeman sextet characteristic of the pure Fe phase (hyperfine field of about 32.8 T) accompanied by two spectral components related to FeSi system: magnetic broad sextet and a quadrupole doublet. The broad sextet could originate from various Fe sites at the interface. The nonmagnetic quadrupole split (QS) doublet is most probably associated with the nonstoichiometric c-Fe1−xSix phase. For larger Si layer thickness (dSi>2 nm) the spectral contribution of the QS doublet increases from 5.7% to about 16%.

Interface Mixing in Fe/Si Multilayers Observed by the In Situ Conductance Measurements

“…The drop of the dynamical resistivity in the second part (II) corresponds to the crystallisation of the amorphous Fe-Si mixture in the layer, and the less steep slope in the third stage (III) reflects the growth of crystalline iron. The presence of the bcc-Fe phase has been confirmed by the X-ray diffraction study and the Mössbauer spectroscopy [6].…”

Magnetic and electric properties of (Fe, Co)/(Si, Ge) multilayers

“…That may suggest that Fe diffuses into the Ge spacer and only nonferromagnetic Fe-Ge phases can be formed. Since all CEMS spectra for Fe/Si MLS contain pronounced QS doublet due to the appearance of nonmagnetic Fe silicides at Fe/Si interfaces [30,31] we expect, that introduction of Ge between Fe and Si prevents the formation of paramagnetic Fe-Si phases, which can be responsible for the observed AF coupling in this system. …”

“…As can be seen, in contrast to Fe/Si MLS, Fe/Ge structure reveals no AF coupling in the whole range of examined Ge spacer thicknesses. Figure 12 [25] exhibits Fe thickness dependence of magnetic moment per surface area ( /S) for [Fe( F )/Ge(2 nm)] 15 and [Fe( F )/Si(2.5 nm)] 15 MLS (see also [30]). From the interception of the straight line with the F axis we conclude, that about 1 nm (0.5 nm at each interface) of sputtered Fe intermixes with Ge and nonferromagnetic Fe-Ge structures are formed.…”

Magnetic properties of Fe films and Fe∕Si∕Fe trilayers grown on GaAs(001) and MgO(001) by ion-beam sputter epitaxy

“…31,34,35 On the other hand, the coupling strength is similar to those found in sputtered, epitaxial, or polycrystalline Fe/ Si multilayers. 31,32,[36][37][38] Further experiments have to be performed to decrease the intermixing. One possibility is to vary the target angle , because the high-energetic Ar ions reflected towards the substrate are likely to intensify interdiffusion processes.…”