Dependence of spin-transfer switching characteristics in magnetic tunnel junctions with synthetic free layers on coupling strength

摘要

Dependence of spin-transfer switching characteristics on the interlayer exchange coupling strength in the MTJs with synthetic free layers of Co_(90)Fe_(10)/Ru/Co_(40)Fe_(40)B_(20) with strong coupling strength was investigated. In the MTJ with the relatively weakly coupled synthetic ferrimagnetic free layer, larger thermal stability (△_0) and lower intrinsic critical current density (J_(c0)) than those of the MTJ with the single free layer were observed. Meanwhile, in the MTJs with the strongly coupled synthetic ferri- or ferromagnetic free layers, very large △_0 and high J_(c0) were observed probably due to high effective magnetic energy barrier. It was found that the MTJ with the relatively weakly coupled synthetic ferrimagnetic free layer is suitable for the STTRAM application.