Magnetic Exchange Interaction Between Fe(110) Layers across a Ag(111) Intervening Layer

We have grown a series of Fe(110)/Ag(111)/Fe(110) sandwich structures using a PHI 430B MBE system and analyzed their magnetic properties using transmission Mössbauer spectroscopy. The heterostructures consisted of two 30-monolayer (ML) 56Fe(110) slabs separated by an intervening Ag(111) layer 2 to 35 ML thick, with a 2 ML 57Fe Mössbauer probe layer placed at one of the Fe/Ag interfaces. We found that temperature dependence of the hyperfine field in the probe layer and the saturation hyperfine field value as well stronly depend on the Ag interlayer thickness. This result demonstrates that there exists an interlayer magnetic exchange interaction between the Fe layers across Ag. In addition, preliminary evidence suggests that this is probably an RKKY interaction.