Asymmetry of the effective bit addressing times in ultrafast MRAM write operation

We study the effective bit addressing times for ultrafast precessional magnetization reversal in magnetic random access memory (MRAM) cells. During field application to an addressed memory cell two different relative field orientations can occur. Either the applied field has a parallel or an antiparallel easy-axis component with respect to the initial cell magnetization. In this work the time dependence of the magnetization motion in these two cases is studied using time-resolved magnetotransport on microscopic magnetic tunnel junction cells. The two cases show a considerably different time evolution. A strong asymmetry of the effective bit addressing times depending on the relative field orientation is found. Implications for fast MRAM operation are discussed.