Abstract:One essential feature in MRAM cells is the spin torque efficiency, which describes the ratio of the critical switching current to the energy barrier. Within this paper it is reported that the spin torque efficiency can be improved by a factor of 3.2 by the use a of dual free layer device, which consists of one layer with perpendicular crystalline anisotropy and a second layer with in-plane crystalline anisotropy. Detailed simulations solving the spin transport equations simultaneously with the micromagnetics equation were performed in order to understand the origin of the switching current reduction by a factor of 4 for the dual layer structure compared to a single layer structure.The main reason could be attributed to an increased spin accumulation within the free layer due to the dynamical tilting of the magnetization within the in-plane region of the dual free layer.Magnetic random access memory (MRAM) has the potential to become a major player in embedded magnetoresitive non-volatile memory technology due to the fast access and write times. An important design guideline in MRAM development is to reduce the critical switching current while maintaining a high thermal stability. Different designs of spin-transfer torque MRAM (STT-MRAM) cells have been proposed in order to reduce the critical current density. Dual pinned layer were proposed in order to reduce the critical current. Here, the second pinned layer has to point in opposite direction to the first pinned layer and it is separated by a second MgO barrier from the free layer. The critical current was reported to be a factor of 2-3 times smaller than that of a single MgO barrier 1 reaching values of the critical current density of j c = 0.02 TA/m² as reported in Ref[ 2 ]. In this reported structure both pinned layers consist of synthetic antiferromagnetically (SAF) coupled and exchange biased layers leading to layer thicknesses of about 40 nm, which reduces the scalability.