Computer simulation of switching characteristics in magnetic tunnel junctions exchange-biased by synthetic antiferromagnets

The free layer switching characteristics in magnetic tunnel junctions with the structure NiFe/AlOx/Co (y nm)/Ru/Co (7-y nm)/FeMn/NiFe are investigated as functions of the relative Co layer thickness and the cell size by computer simulation. The bias field varies linearly with y, and the relative Co layer thickness dependence of the bias field is greater at smaller cell dimensions. At y=4, the bias field of the free layer remains nearly unchanged with the cell size, due to the balance of the stray field contribution from neighboring layers. The contribution from the lower permalloy layer (next to the FeMn) is found to be not small. The calculated hysteresis loops are in qualitative agreement with the experimental results