Magnetic Properties of Exchange-Coupled Dual-Layer SmTbCo Thin Films

Exchange-coupled SmTbCo dual-layer media are prepared by an r.f magnetron sputtering system and their magnetic properties are investigated. The prepared SmTbCo dual layer is composed of a 340 emu/cm3 TM-rich readout layer and a 5.80 kOe RE-rich memory layer, meeting the requirements of high saturation magnetization and large coercivity for hybrid recording. Through exchange coupling, the coercivity of the high-saturation-magnetization SmTbCo layer is greatly enhanced from 1.85 to 5.96 kOe. The calculated interface wall energy for Sm6.65Tb12.35Co81 (20 nm)/Sm1.22Tb42.16Co56.62 (20 nm) is about 3.85 erg/cm2. The reversal magnetization of the SmTbCo exchange-coupling dual-layer films is analysed based on a micro-magnetic model.