Large Dzyaloshinskii-Moriya interaction and field-free topological chiral spin states in two-dimensional alkali-based chromium chalcogenides

Abstract

Noncentrosymmetric ferromagnetic systems with large Dzylochinskii-Moriya interaction (DMI) have gained intensive attention for hosting topologically protected solitons such as skyrmions and bimerons. Recently, a series of two-dimensional (2D) Li- and Na-based chromium chalcogenides has been theoretically predicted to be a new family of intrinsic inversion asymmetric ferromagnets. Here, by combining first-principles calculations and atomistic spin model simulations, we unveil that there is very large DMI in these series of 2D alkali-based chromium chalcogenides, which enables a variety of filed-free topological spin textures in these structures. Furthermore, we find robust hole-doping tunable DMI in the ${\mathrm{LiCrSe}}_{2}$ and ${\mathrm{NaCrSe}}_{2}$ monolayers. Our finding opens up further possibilities toward 2D materials in spintronic devices.