Micromagnetic simulation of the temperature dependence of the switching energy barrier using string method assuming sidewall damages in perpendicular magnetized magnetic tunnel junctions

Abstract

The influence of magnetic damages at the sidewall of perpendicular magnetic tunnel junctions (p-MTJs), which are the core devices of spin-transfer-torque magnetoresistive random-access memory (STT-MRAM), is discussed based on the thermal stability factor, Δ, double-logarithmic plot of normalized switching energy barrier, E, and saturation magnetization, Ms, and their exponential slope, n. Δ was calculated using the string method under the simulation conditions of domain wall motion switching. n increased with the increasing thickness of the damaged layer of the sidewall. Notably, the sidewall damage can be explained by the reduction in Ms and exchange stiffness constant, As, rather than the interfacial perpendicular anisotropy. The findings of this study are important for controlling and improving the process damage in the mass production of p-MTJs in STT-MRAM.