Single ferromagnetic layer magnetic random access memory

Abstract

We propose a magnetic random access memory (MRAM) device in which both the writing and reading processes are realized within a single ferromagnetic (FM) layer. The FM layer is sandwiched between layers of heavy element and oxide to enhance the Rashba spin-orbit coupling (RSOC). When the in-plane FM moments are oriented at some intermediate angle to the current direction, the RSOC effect induces a spin accumulation in the FM layer, which in turn generates a Rashba spin torque field via the s-d exchange interaction. This field acts as the writing field of the memory device. The RSOC also induces a charge accumulation in the transverse direction via the inverse spin Hall effect (ISHE), which can be used to realize the memory read-out. The writing and read-out processes of the proposed memory are modeled numerically via the non-equilibrium Green's function technique. Besides the advantages of Rashba spin torque writing, i.e., no spin injection and symmetrical data-writing process, this single FM layer MRAM design does away with having a giant magnetoresistive or magnetic tunnel junction multilayer structure by utilizing the ISHE for the read-out process. © 2013 AIP Publishing LLC.