Compact Model of Subvolume MTJ and Its Design Application at Nanoscale Technology Nodes

Abstract

The current-induced perpendicular magnetic anisotropy magnetic tunnel junctions (p-MTJs) offer a number of advantages, such as high density and high speed. As p-MTJs downscale to ~40 nm, further performance enhancements can be realized thanks to high spin-torque efficiency, i.e., lower critical current density and higher thermal stability. In this paper, we investigate the origin of high spin-torque efficiency and give a phenomenological theory to describe the critical current reduction due to the subvolume activation. Based on various physical theories and structural parameters, a compact model of nanoscale MTJ is developed and demonstrates a satisfactory agreement with experimental results. Dynamic, static, and stochastic switching behaviors have been addressed and validated. Then, we perform mixed simulations for hybrid MTJ/CMOS read/write circuits, magnetic random access memory, and magnetic flip-flop to evaluate their performance. Analyses of energy consumption are given to show the prospect of MTJ technology node miniaturization.