Perpendicular Magnetic Anisotropy Engineering for Skyrmion Thermal Stability and Pulsed-Current-Driven Dynamics in a Z-Junction Nanotrack

Magnetic skyrmions are promising information carriers for nanoscale spintronic devices, but their use in confined structures requires control of both topological survival and current-driven motion. We investigate perpendicular magnetic anisotropy engineering in a Z-junction nanotrack using micromagnetic simulations. The anisotropy is varied from 0.70 to 1.00 MJ/m3 at 300 K for a junction depth of 50 nm, junction width of 5 nm, and pulsed current density of 1.8 × 1012 A/m2. Five independent thermal realisations are considered for each finite-temperature condition. No annihilation is observed for Ku = 0.70–0.90 MJ/m3 during the 63 ns observation interval, whereas all five realisations at 0.95 and 1.00 MJ/m3 undergo annihilation within approximately 9–10 ns. The 0.90 MJ/m3 case remains topologically intact despite strong compression. Additional in-plane mesh refinements reproduce survival at 0.90 MJ/m3 and annihilation at 1.00 MJ/m3. The selected compact reference condition Ku = 0.85 MJ/m3 is then examined from 0 to 500 K, with a deterministic reference at 0 K. The trajectories show preservation of the skyrmion-like topological state within the available observations, together with temperature-dependent positional, radial, and velocity variations. These results distinguish finite-time topological survival from dynamical reproducibility. The temperature sweep describes thermal-noise effects within a fixed-parameter model; it does not establish a thermally activated lifetime, a universal optimal anisotropy, or an experimental device operating-temperature range.