The concept and fabrication of exchange switchable trilayer of FePt/FeRh/FeCo with reduced switching field

We report the concept and fabrication of exchange switchable trilayer of FePt/FeRh/FeCo with reduced switching field for heat assisted magnetic recording (HAMR). A thin layer of FeRh is sandwiched between L10 FePt and magnetically soft FeCo. At room temperature, FePt and FeCo are magnetically isolated by the antiferromagnetic FeRh layer. After the metamagnetic transition of FeRh layer by heating, FePt and FeCo are exchange-coupled together through ferromagnetic FeRh layer. Therefore, the switching field of FePt can be greatly reduced via exchange-spring effect. Simulation work was carried out to understand the exchange coupling strength and the FeCo thickness effects on the switching field reduction. It is found that switching field decreases with the increase of exchange coupling strength and FeCo thickness. The trilayer films were also successfully fabricated. A clear change of reversal mechanism from two-step to one-step switching upon heating was observed and a 3-time switching field reduction was dem...