Micromagnetic Analysis of Statistical Switching in Perpendicular STT-MRAM With Interfacial Dzyaloshinskii–Moriya Interaction

The technological implementation of STT-magnetic random-access memory (MRAM) in real devices needs a complete description of the statistical switching behavior at room temperature. In this paper, we investigate, by means of a full micromagnetic model, the effect of the interfacial Dzyaloshinskii-Moriya interaction (IDMI) on the critical current density and probability density function (PDF) of the switching time in perpendicular STT-MRAMs. We show that for large enough values of the symmetric exchange interaction, the negative effect of the IDMI on the critical current is strongly reduced. In addition, a comprehensive analysis of the four main statistical moments (mean, standard deviation, skewness, and kurtosis) points out that to fit the switching time PDF in order to maintain a quadratic error at least one order of magnitude smaller than skew normal PDF, a Pearson type IV PDF has to be used also in presence of the IDMI.