LAUSR

We investigate the dependence of magnetic properties on the post-annealing temperature/time, the thickness of the soft ferromagnetic electrode, and the Ta dusting layer in the pinned electrode as well as their correlation with the tunnel magnetoresistance ratio, in a series of perpendicular magnetic tunnel junctions of materials sequence Ta/Pd/IrMn/CoFe/Ta(x)/CoFeB/MgO(y)/CoFeB(z)/Ta/Pd. We obtain a large perpendicular exchange bias of 79.6 kA/m for x = 0.3 nm. For stacks with z = 1.05 nm, the magnetic properties of the soft electrode resemble the characteristics of superparamagnetism. For stacks with x = 0.4 nm, y = 2 nm, and z = 1.20 nm, the exchange bias presents a significant decrease at post-annealing temperature T ann = 330 ° C for 60 min, while the interlayer exchange coupling and the saturation magnetization per unit area sharply decay at T ann = 340 ° C for 60 min. Simultaneously, the tunnel magnetoresistance ratio shows a peak of 65.5 % after being annealed at T ann = 300 ° C for 60 min, with a significant reduction down to 10 % for higher annealing temperatures ( T ann ≥ 330 ° C) and down to 14 % for longer annealing times ( T ann = 300 ° C for 90 min). We attribute the large decrease of tunnel magnetoresistance ratio to the loss of exchange bias in the pinned electrode.We investigate the dependence of magnetic properties on the post-annealing temperature/time, the thickness of the soft ferromagnetic electrode, and the Ta dusting layer in the pinned electrode as well as their correlation with the tunnel magnetoresistance ratio, in a series of perpendicular magnetic tunnel junctions of materials sequence Ta/Pd/IrMn/CoFe/Ta(x)/CoFeB/MgO(y)/CoFeB(z)/Ta/Pd. We obtain a large perpendicular exchange bias of 79.6 kA/m for x = 0.3 nm. For stacks with z = 1.05 nm, the magnetic properties of the soft electrode resemble the characteristics of superparamagnetism. For stacks with x = 0.4 nm, y = 2 nm, and z = 1.20 nm, the exchange bias presents a significant decrease at post-annealing temperature T ann = 330 ° C for 60 min, while the interlayer exchange coupling and the saturation magnetization per unit area sharply decay at T ann = 340 ° C for 60 min. Simultaneously, the tunnel magnetoresistance ratio shows a peak of 65.5 % after being annealed ...