MgO/CoFeB/Ta/CoFeB/MgO Recording Structure in Magnetic Tunnel Junctions With Perpendicular Easy Axis

Junction size (D) dependence of thermal stability (Δ) factor and intrinsic critical current (I_C0) were investigated for MgO/CoFeB/Ta/CoFeB/MgO recording structure in magnetic tunnel junctions (MTJs) having a CoFeB reference layer and a synthetic ferrimagnetic (SyF) reference layer. Δ of the recording structure shows almost constant value down to 40 nm, whereas I_C0 shows a linear dependence on the recording layer area, as similarly observed in recording structure with single-interface. Average absolute intrinsic critical current density is 3.5 MA/cm², which is comparable to previously reported value for recording structure with single-interface. A MgO/CoFeB(1.4)/Ta(0.4)/CoFeB(1.0)/MgO double-interface recording structure in MTJ with SyF reference layer shows Δ of 59 at D = 29 nm.