Oscillations of the Curie temperature and interlayer exchange coupling in magnetic trilayers

The onset of long-range magnetic order in exchange-coupled epitaxial Co/Cu/ Ni trilayers, 2-4 monolayers (ML) each, on Cu(001) is studied by element-sp ecific x-ray magnetic circular dichroism between 30 and 300 K in ultrahigh vacuum. Oscillations of the enhancement of the ordering temperature of Ni ( Delta T (Ni)) by more than 40 K are measured as a function of interlayer ex change interaction by varying the Cu(001) spacer thickness. Below a Cu thic kness of 2.3 ML antiferromagnetic coupling is measured. The period, phase, and amplitude of the Delta T (Ni) oscillations an in excellent agreement wi th the theoretical prediction for the short- and long-period oscillations o f the interlayer exchange coupling.