Interlayer coupling mechanisms in amorphous CoxSi1-x/Si multilayers

Interlayer coupling has been studied in amorphous CoxSi1-x/Si multilayers with a Curie temperature close to room temperature. Results show an antiferromagnetic coupling mechanism that is clearly detectable in the temperature range above 250 K. This antiferromagnetic coupling presents a decrease with increasing Si spacer thickness, but with decay lengths of the order of several nm, longer than the typical values for metallic spacers. Its strength, typically of the order of 10(-5) erg/cm(2), decreases monotonically with increasing temperature, which could be compatible with a mechanism associated with the presence of defects or magnetic impurities in the interlayers. At lower temperatures, due to the increase in saturation magnetization, the magnetic behavior of the multilayers is dominated by other ferromagnetic coupling mechanisms of magnetostatic origin (Neel's "orange peel" and domain-wall coupling) and the antiparallel alignment of the layers is not observed any more.