Magnetoresistance associated with antiferromagnetic interlayer coupling spaced by a semiconductor in Fe /Si multilayers

Multilayer Fe/Si films with constant Fe thickness (2.6 nm) and variable Si thickness are investigated. Negative magnetoresistance is observed and two different temperature dependences are found as a function of Si thickness. For tSi=1.2 nm, the magnetoresistance decreases with temperature decrease. For tSi>1.5 nm, the magnetoresistance increases (weakly) with temperature decrease. The magnetoresistance is attributed to spin-dependent scattering caused by antiferromagnetic layer coupling across a semiconducting spacer: narrow gap iron silicide for thin Si spacer layers and amorphous Si for thicker spacer layers.