Temperature-dependent interlayer exchange coupling strength in synthetic antiferromagnetic [Pt/Co]2/Ru/[Co/Pt]4 multilayers**Project supported by the National Natural Science Foundation of China (Grant No. 11704191), the Jiangsu Specially-Appointed Professor, the Natural Science Foundation of Jiangsu Province of China (Grant No. BK20171026), and the Six-Talent Peaks Project in Jiangsu Province, China (Grant No. XYDXX-038).

Abstract

In this work, we experimentally investigated the thermal stability of the interlayer exchange coupling field (Hex) and strength (–Jiec) in synthetic antiferromagnetic (SAF) structure of [Pt(0.6)/Co(0.6)]2/Ru(tRu)/[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 Hex 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 –Jiec. It is found that the interlayer coupling in the multilayers is very sensitive to the thickness of Ru and temperature. The Hex 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 (Hex = 3.19 KOe, –Jiec = 1.97 erg/cm2 for tRu = 0.6 nm, the unit 1 Oe = 79.5775 A·m–1), which was higher than the previous studies.