Size and shape of skyrmions for variable Dzyaloshinskii–Moriya interaction and uniaxial anisotropy

Abstract

We have performed micromagnetic simulations to study the formation of skyrmions from an initial single bubble domain state in ferromagnetic elements with different shapes having perpendicular anisotropy. The strength of Dzyaloshinskii–Moriya interaction (D) and uniaxial anisotropy (K) are varied to elucidate the regime in which skyrmion formation can take place. It is found that for a certain combination of D and K, skyrmion formation does not happen. Further, we also observed that for large D and small K values, finite size effect dominates, which in turn hinders the formation of typical Néel (spherical) skyrmions. However, the resulting magnetic phase is skyrmionic in nature and has different shapes. We also have found that the shape of the magnetic nano element has a significant role in determining the final magnetic state in addition to the competing D and K values.