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 340emu/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 5.96kOe. The calculated interface wall energy for Sm_6.65Tb_12.35Co₈₁ (20nm)/Sm_1.22Tb_42.16Co_56.62 (20nm) is about 3.85erg/cm². The reversal magnetization of the SmTbCo exchange-coupling dual-layer films is analysed based on a micro-magnetic model.