Construction of a Room-Temperature Pt/Co/Ta Multilayer Film with Ultrahigh-Density Skyrmions for Memory Application

Magnetic skyrmions are chiral quasiparticles that show promise for storage of information. At present, the achievable skyrmion density (η Sk ) is generally low (10–20 μm –2 ) because of the lack of effective manipulation. Here, both the magnetic anisotropy ( K eff ) and interfacial Dzyaloshinskii–Moriya interaction (DMI) of [Pt/Co/Ta] n multilayer films are elaborately modulated by changing the Co thickness ( t Co ) to study the η Sk dependence of intrinsic properties of the films systematically. The experimental and simulated results confirm that both the DMI and K eff have significant modifications on η Sk, and their respective contributions vary with t Co . Only when the magnetic anisotropy transits from out-of-plane to in-plane at an appropriate t Co range (1.8–2.1 nm) does the K eff decrease and the DMI increase with the t Co . Both the factors are favorable to the skyrmion formation and increase the density synergistically, toggling a maximal η Sk value of 45 μm –2 . These findings provide a criterion for designing the high η Sk magnetic film, which may advance the development of high-density skyrmion-based magnetic memorizers.