WRITE ERROR MODELING OF SPIN-ORBIT-TORQUE SWITCHED MAGNETIC MEMORY IN PRESENCE OF EXTERNAL MAGNETIC FIELD

Abstract

The write process in the magnetic random-access memory (MRAM) bit is inherently stochastic, resulting in a wide distribution of switching times. This thesis aims to investigate write process of spin-orbit-torque (SOT) MRAM cell for immunity against external stray field exposure. Bit error rates for write operations are calculated using numerical models of SOT-induced magnetization dynamics coupled with thermal noise. Using a code implementing numerical integration of Landau-Lifshitz-Gilbert equation including spin-transfer-torque, spin-orbit-torque and thermal field terms, stochastic switching process of a perpendicular magnetic bit is simulated. Further, SOT switching process in presence of varying external field and varying applied current density is studied at the limit of zero temperature followed by finite temperature. Phase diagram of switching probability obtained from the simulations is compared with previously reported data.