Exponential dependence of the interlayer exchange coupling on the spacer thickness in MBE-grown Fe/SiFe/Fe sandwiches

The structure and interlayer exchange coupling in MBE-grown Fe/SiFe/Fe has been investigated. From structural analysis with LEED and from magnetic analysis with the magneto-optical Kerr effect, it is concluded that the Si spacer transforms into an ordered Si0.5Fe0.5 alloy. A strong antiferromagnetic coupling is found (maximum -2.0mJ/m2), the strength of which varies exponentially as a function of the spacer thickness. This behavior can be explained within the framework of recent coupling theories