Interlayer exchange coupling and perpendicular electric transport in Fe/Si/Fe trilayers

Abstract

The interlayer exchange coupling and the perpendicular magnetoresistance of Fe/Si/Fe systems have been investigated within the fully relativistic screened Korringa-Kohn-Rostoker method and the Kubo-Greenwood equation considering interdiffusion effects, i.e., inhomogeneous Fe-Si alloy formation at the interfaces. It is shown that the experimentally observed strong antiferromagnetic interlayer exchange coupling is caused by the formation of Fe-Si alloys at the interface. Furthermore, our calculations give evidence that the small magnetoresistance, which has been observed experimentally in Fe/Si/Fe trilayers has a similar origin. The results presented here give no evidence for a direct connection between the magnetoresistance and interlayer exchange coupling in Fe/Si/Fe systems.

Ultrafast thermally induced magnetic switching in synthetic ferrimagnets

“…The strength of the exchange interaction determines the timescale of the switching process and the rate of transfer of angular momentum between the sublattices and so should be as strong as possible. Depending on the system there is some disparity between the values of exchange measured experimentally 11,21 and calculated theoretically, 22 and so we assume an intermediate value of the interlayer exchange interaction of $1=5 that of the bulk FePt exchange ðJ The FePt layer is initially demagnetized by the heat pulse and switches direction under the influence of the exchange field from the Fe, while the Fe layer itself retains a higher degree of order. As the electron system cools the FePt recovers its order along the-z direction, i.e., it switches its magnetization.…”

Electric transport perpendicular to the planes

“…However, the decrease is accompanied by oscillations, which depend on the number of Cr layers. In order to understand the oscillations we have calculated the energy difference between the FM and AF state, (AF) (FM) E E E D = -in dependnce of n. This has been done by applying the magnetic force theorem [35,37], i.e. only the FM reference state is calculated selfconsistently.…”

“…This system tends to build CsCl-like FeSi alloys near the interfaces [38]. In our calculations we have considered an interdiffusion region that is restricted to the direct interface [37] The GMR obtained from Eq. (2) for different interdiffusion concentrations c is shown in Fig.…”

“…(25), has been obtained from the fully-relativistic spin-polarized version of the screened Korringa-Kohn-Rostoker (SKKR) method for layered systems developed by Weinberger and Szunyogh [35,36]. Technical details concerning the calculation of the electric and magnetic properties can be found in [33,37]. Basically, the GMR is calculated for different numbers of NM spacer layers.…”

Diffusive magnetoresistance and interlayer exchange coupling of the ferromagnet–semiconductor layered systems Fe/GaAs and Fe/Ge

“…The influences caused by interdiffused interfaces have been extensively investigated by Herper et al [18] for the Fe/Si/Fe junction, by means of the Kubo-Greenwood approach, in a fully-relativistic formulation. Assuming an FeSi alloy formation at the interface lead to a significance reduction in the MR.…”