Oscillation of the interlayer coupling in Co/Au(111)/Co

An oscillatory interlayer coupling in Co/Au(111)/Co has been obtained from polar Kerr hysteresis loop measurements on a molecular-beam-epitaxy-grown 50 Å Au/2 Å Co/0-40 Å Au wedge/7 Å Co/20 Å Au sample deposited on a Cu(111) single crystal. The period of the coupling is seen to increase from 11 to 14 Å with increasing Au thickness, indicating a preasymptotic behavior. The asymptotic period of 14±1 Å is larger than the theoretically expected period of 11.4 Å. The observation of coupling up to 40 Å Au will be discussed in relation to the general absence of coupling in evaporated Co/Cu(111)/Co samples.