Micromagnetic analysis of magnetic memory

Magnetoresistive Random Access Memory (MRAM) has become a viable technology that not only can replace the current FLASH memory for nonvolatile memory applications, but also could revolutionize the present computer memory architecture by replacing DRAM and SRAM. However, the key to a success of commercial application for MRAM technology lies on the ability of achieving robust magnetic switching of the memory elements. In this thesis, the micromagnetic switching behavior of various MRAM designs are analyzed via micromagnetic modeling. By combining the classic micromagnetic theory with the Landau-Lifshitz-Gilbert gyromagnetic equations, dynamic magnetic performance of the memory elements are investigated. The work focuses on establishing the correlation between the magnetic switching characteristics and geometric memory element design, as well as material properties and material microstructure. The results presented in this thesis provide a systematic understanding of the memory state switching in two major MRAM designs at present, namely, the pseudo-spin-valve and the magnetic tunneling junction designs. Insights to control the magnetic switching field for a memory element in both designs are provided. To certain extends, predictions on scaling down in size for the memory elements are made based on systematic calculations. Addressibility of individual memory elements in a memory array for write/read operations is also studied for the magnetic tunneling junction MRAM design. It is concluded that the ability of controlling the geometric shaping of the memory elements in a practical manufactory environment is critical for a commercial success of the MRAM technology.