Quantifying the Impact of Arbitrary Magnetic Field Perturbation on the Write Error Rate of Spin-Orbit-Torque Random Access Memory

Abstract

Spin-orbit-torque (SOT) magnetic random access memory (MRAM) is an emerging nonvolatile memory technology that uses the SOT effect to switch the magnetization direction of magnetic storage elements. Compared with spin-transfer torque (STT) MRAM, SOT-MRAM exhibits a faster write speed and higher endurance, making it a promising candidate for next-generation high-performance embedded memory or cache applications. However, the magnetic storage characteristics of MRAM render it susceptible to perturbation from external magnetic fields. In this study, we systematically and quantitatively investigated the impact of an arbitrary magnetic field $\mu _{0}\mathbf {H}_{\text {arb}}$ orientation ( $\theta $ , $\varphi $ ) on the write error rate (WER) of SOT-MRAM based on the Fokker-Planck equation (FPE) method and elucidated the underlying physical mechanism of magnetic field direction sensitivity. The results indicate that variations in ( $\theta $ , $\varphi $ ) can lead to different degrees of shift in the WER-switching time curve, eventually causing fluctuations in the WER at a fixed write pulsewidth. This phenomenon originates from the modulation of the magnetization probability density distribution by the angle between $\mu _{0}\mathbf {H}_{\text {arb}}$ and magnetization vector m. This research provides crucial insights into the effect of $\mu _{0}\mathbf {H}_{\text {arb}}$ on the WER of SOT-MRAM and emphasizes the importance of parameter adjustments to enhance the magnetic immunity of WER to $\mu _{0}\mathbf {H}_{\text {arb}}$ for improved write reliability under complex operating conditions.