Temperature-dependent interlayer exchange coupling strength in synthetic antiferromagnetic [Pt/Co]2/Ru/[Co/Pt]4 multilayers

In this work, we experimentally investigated the thermal stability of the interlayer exchange coupling field (H-ex) and strength (-J(iec)) in synthetic antiferromagnetic (SAF) structure of [Pt(0.6)/Co(0.6)](2)/Ru(t(Ru))/[Co(0.6)/Pt(0.6)](4) multilayers with perpendicular anisotropy. Depending on the thickness of the spacing ruthenium (Ru) layer, the observed interlayer exchange coupling can be either ferromagnetic or antiferromagnetic. The H-ex were studied by measuring the magnetization hysteresis loops in the temperature range from 100 K to 700 K as well as the theoretical calculation of the -J(iec). It is found that the interlayer coupling in the multilayers is very sensitive to the thickness of Ru and temperature. The H-ex exhibits either a linear or a non-linear dependence on the temperature for different thickness of Ru. Furthermore, our SAF multilayers show a high thermal stability even up to 600 K (H-ex = 3.19 kOe, -J(iec) = 1.97 erg/cm(2) for t(Ru) = 0.6 nm, the unit 1 Oe =79.5775 A.m(-1)), which was higher than the previous studies.