Advanced Switching MRAM Modes

This chapter describes three promising new modes of magnetoresistive random‐access memory (MRAM) cells that are currently under research and development at the time of this manuscript preparation: current‐induced domain‐wall motion mode (CIDM), spin orbit torque (SOT) mode, precession‐toggle mode. All are based on magnetic tunnel junction (MTJ) technology, and all promise very fast access time. The MTJ is switched in a way similar but different from the pure spin‐transfer mechanism. Both CIDM memory cell and SOT memory cell are configured in 1M‐2T (1 MTJ, 2 transistors) cell topology. The precession‐toggle mode MRAM is based on the voltage‐control magnetic anisotropy effect. The chapter compares the properties of advanced switching mode MRAMs against field‐MRAM and spin‐transfer torque‐MRAM. The MRAM cell size has been predominantly determined by the size of the cell transistor and the number of connecting wire per bit cell and wire pitch, not the MTJ.