Assembling Diverse Skyrmionic Phases in Fe₃GeTe₂ Monolayers

Abstract Skyrmionic magnetic states are promising in advanced spintronics. This topic is experiencing recent progress in 2D magnets, with, for example, a near 300 K Curie temperature observed in Fe₃GeTe₂. However, despite previous studies reporting skyrmions in Fe₃GeTe₂, such a system remains elusive, since it has been reported to host either Néel‐type or Bloch‐type textures, while a net Dzyaloshinskii–Moriya interaction (DMI) cannot occur in this compound for symmetry reasons. It is thus desirable to develop an accurate model to deeply understand Fe₃GeTe₂. Here, a newly developed method adopting spin invariants is applied to build a first‐principle‐based Hamiltonian, which predicts colorful topological defects assembled from the unit of Bloch lines, and reveals the critical role of specific forms of fourth‐order interactions in Fe₃GeTe₂. Rather than the DMI, it is the multiple fourth‐order interactions, with symmetry and spin–orbit couplings considered, that stabilize both Néel‐type and Bloch‐type skyrmions, as well as antiskyrmions, without any preference for clockwise versus counterclockwise spin rotation. This study also demonstrates that spin invariants can be used as a general approach to study complex magnetic interactions.