Very large Dzyaloshinskii-Moriya interaction in two-dimensional Janus manganese dichalcogenides and its application to realize field-free skyrmions

Abstract

The Dzyaloshinskii-Moriya interaction (DMI), which only exists in noncentrosymmetric systems, is responsible for the formation of exotic chiral magnetic states. However, it is absent in most theoretical predictions and experiments for two-dimensional (2D) magnetic thin films so far. Here, using first-principles calculations, we demonstrate that significant DMI can be obtained in a series of Janus monolayers of manganese dichalcogenides MnXY with broken inversion symmetry. In particular, the DMI amplitudes of MnSeTe and MnSTe are comparable to those of state-of-the-art ferromagnet/heavy metal (FM/HM) heterostructures. We find that the DMI of these Janus monolayers is dominated by the heavy chalcogen atoms. In addition, atomistic spin simulations show that various chiral spin textures including spin helix and skyrmion can be stabilized without external field in the MnXY monolayers. The present results pave the way for new device concepts utilizing chiral magnetic structures in the emerging 2D ferromagnetic materials.