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/cm² for t _Ru = 0.6 nm, the unit 1 Oe = 79.5775 A·m ^–1), which was higher than the previous studies. (special topic)