Oscillations with a period of two Cr monolayers in the antiferromagnetic exchange coupling in a (001) Fe/Cr/Fe sandwich structure

Oscillations with a period of two Cr monolayers were measured in the antiferromagnetic exchange coupling between Fe magnetizations separated by Cr. The coupling was measured on a sample consisting of a Au(20 Å)/Fe(50 Å)/Cr(0–18 Å wedge) film deposited by molecular-beam epitaxy on a Fe[100] single-crystal ‘‘whisker.’’ The Cr and Fe grew monolayer by monolayer as monitored by reflection high-energy-electron diffraction. The coupling was determined from the magneto-optic Kerr effect. It was antiferromagnetic for 5–18 Å Cr with four strong peaks and a maximum value of -0.60 mJ/${\mathrm{m}}^2$ for eight monolayers of Cr.