MAGNETIC AND TRANSPORT-PROPERTIES OF SPUTTERED FE SI MULTILAYERS/

The structural, magnetic and transport properties of sputtered Fe/Si m ultilayers were studied. The analyses of the data of the X-ray diffrac tion, resistance and magnetic measurements show that heavy atomic inte rdiffusion between Fe and Si occurs, resulting in multilayers of diffe rent complicated structures according to different sublayer thicknesse s. The nominal Fe layers in the multilayers generally consist of Fe la yers doped with Si; ferromagnetic Fe-Si silicide layers and nonmagneti c Fe-Si silicide interface layers, while the nominal Si spacers turn o ut to be Fe-Si compound layers with additional amorphous Si sublayers only under the condition either t(Si) greater than or equal to 3 nm fo r the series [Fe(3 nm)/Si(t(Si))](30) or t(Fe) < 2 nm for the series [ Fe(t(Fe))/Si(1.9 nm)](30) multilayers. A strong antiferromagnetic (AFM ) coupling and negative magnetoresistance (MR) effect, about 1%, were observed only in multilayers with iron silicide spacers and disappeare d when alpha-Si layers appear in the spacers. The dependences of MR on t(Si) and on bilayer numbers N resemble the dependence of AFM couplin g. The increase of MR ratio with increasing N is mainly attributed to the improvement of AFM coupling for multilayers with N. The t(Fe) depe ndence of MR ratio is similar to that in metal/metal system with predo minant bulk spin dependent scattering and is fitted by a phenomenologi cal formula for GMR. At 77 K both the MR effect and saturation field H -s increase. All these facts suggest that the mechanisms of the AFM co upling and MR effect in sputtered Fe/Si multilayers are similar to tho se in metal/metal system.