Study of precessional switching speed control in voltage-controlled perpendicular magnetic tunnel junction

Abstract

We study the characteristics of the precessional switching induced by voltage control of magnetic anisotropy (VCMA) in back-end-of-line (BEOL)-compatible perpendicular magnetic tunnel junction devices. Using micromagnetic simulation, we find three operation regimes differentiated by zero excess energy, lower boundary, zero energy barrier, and upper boundary. Experimentally, the switching speed (fs) is characterized by two phases: non-precession and acceleration. Non-precession is a thermal mediated phase, where fs cannot be deduced, while in acceleration, both the higher electric field (EF) and in-plane field (Bx) increase fs progressively. We find that the intrinsic thresholds can be retrieved by linear extrapolation of fs as a function of EF. Those thresholds and experimental results are in good agreement with the simulation. In addition, we numerically calculate the characteristic switching speed of 2γ∗mz∗Bx and verify it experimentally. This work provides insights into the VCMA-induced precessional switching, including detailed understandings of the switching mechanism and modeling of switching speed for reliable write duration control for practical applications.