Reduction of Offset Field in Top-Pinned MTJ With Synthetic Antiferromagnetic Free Layer

摘要

We found that the offset field (H) of a top-pinned magnetic tunnel junction (MTJ) with a CoPd/Ru/Ta/CoFeB-synthetic antiferromagnetic (SAF) free layer can be reduced by controlling the exchange coupling energy (J) value. A micromagnetic simulation was used to derive the direct relation between the J) of a CoPd/Ru/Ta/CoFeB-SAF free layer and the H) of a top-pinned MTJ with the SAF free layer. In addition, we found that the J) value can be controlled by changing the thickness of the Ta spacer between the CoPd and CoFeB layers. As a result, we fabricated a top-pinned MTJ with a SAF free layer that eliminated the offset field and made it possible to improve the thermal stability.