ABSTRACT
Spin-transfer torque random access memory (STT-RAM) is one of the frontrunners in spin-based memory technology. A proper model for spin torque-induced switching should include thermal effects, which provide the initial torque to nudge the magnetization away from stagnation points along the energy landscape, while at the same time hindering the motion of the magnetization on its journey past stagnation. The critical current densities for spin torque switching in STT-RAMs is nonetheless too high for commercial applications, prompting intense investigation into material properties of the free layer. The chapter introduces the macrospin simulator that solves the landau–lifshitz–gilbert equation, and shows benchmarks with experimental results. It outlines the critical switching currents and thermal stabilities for the in-plane, perpendicular, and partially perpendicular ferromagnetic free layers. The chapter describes the variation in switching speeds across the material classes for a given switching current density, providing a path for the STT-RAM industry for fast, reliable switching.
