Spin-Flip Behaviour Observed in (Pt/Co)₅/Ru/(Co/Pt)₅ Films

(Pt/Co)₅/Ru/(Co/Pt)₅ films with different Ru thicknesses were prepared by magnetron sputtering. Oscillatory behaviour of effective perpendicular anisotropy and remanence in the (Pt/Co)₅/Ru/(Co/Pt)₅ films as a function of the thickness of Ru has been first observed, from which we can obtain the conclusion that the synthetic spin in the (Pt/Co)₅/Ru/(Co/Pt)₅ films rotates from the vertical direction to the in-plane one periodically with the change of the thickness of the spacer layer of Ru. The oscillatory period is about two atomic layers of Ru and different from the long and short oscillatory periods of the interlayer antiferromagnetic coupling in Co/Ru/Co, Co/Cu/Co, and Fe/Cr/Fe, etc.