The Micromagnetics of Magnetoresistive Random Access Memory

Abstract

This review presents the fundamental understanding of micromagnetic behavior in patterned magnetic thin film elements, in particular, the magnetic switching characteristics of various magnetoresistive random access memory (MRAM) device designs. Application of micromagnetic theory to modeling of MRAM devices will be introduced. Comparison between modeling and experimental studies is presented for the validity of the modeling technique. In the review, pseudo spin-valve, magnetic tunneling junction, and vertical giant magnetoresistive multilayer (VMRAM) designs are discussed in detail in terms of their magnetic switching robustness and area storage densities. Micromagnetic analysis of magnetic switching properties of various shaped memory elements are presented. Through the analysis, it becomes evident that the key to the success of the MRAM technology is the robustness of magnetic switching in a device design. It is concluded that VMRAM design provides the most robust switching characteristics and highest storage density due to the flux-closure mode that generates no stray field and no demagnetization field.