Exchange coupling in symmetric Co/Cr/Co trilayer: a Brillouin light scattering study

A detailed Brillouin light scattering (BLS) investigation of spin waves in Co(20 nm)/Cr(dCr)/Co(20 nm) symmetric trilayer with wedge-shaped Cr interlayer has been carried out. Results showed that the interlayer exchange coupling oscillates, with antiferromagnetic peaks near the Cr layer thickness of 0.7 and 2.5 nm. These oscillations can be satisfactorily reproduced by a calculation based on the RKKY theory. An independent confirmation of the results obtained by BLS has been derived by measuring the saturation field of the longitudinal hysteresis loop as a function of the Cr thickness by magneto-optic Kerr effect magnetometry. Using the magnetic parameter determined by the above analysis, we have calculated the Brillouin cross section for the different Cr spacer thickness obtaining a very good agreement with the measured spectra.