Spin Flop Switching of the Guided Synthetic Antiferromagnet MRAM

A magnetoresistance random access memory (MRAM) with a guided synthetic antiferromagnet (SAF) and direct writing scheme is presented to reduce the writing time. The MRAM cell includes not only the balanced SAF trilayers but also one more guiding layer, which is weakly exchange-coupled with one of the SAF layers. The two orthogonally oriented digital and word lines are aligned at 45deg with respect to the easy axis of the cell. With the exchange-coupling field from the guiding layer, the MRAM cell can be written directly by the combined field induced by current of the digital and word line. However, the cell cannot be switched by any single field induced by either current due to the balanced SAF structure before saturation. The switching field has been reduced and the writing operation margin has been improved with the use of the exchange-coupling field. Both simulation and the experiments have been carried out to verify this scheme. The write operation margin-H _disturb/H_sw of more than 4.3 has been achieved for the magnetic tunnel junction MRAM cell