First-Principles Characterization of Chiral Helimagnetism of Cr_1/3NbS₂ and Cr_1/3TaS₂

Chiral helimagnets have attracted significant attention in recent years for their potential in next-generation spintronic technologies. However, accurately calculating helimagnetic properties remains a challenge. In this work, we report a general approach to describing helimagnetic spin structures using first-principles density functional theory (DFT) calculations. This method provides a precise description of the helical magnetic structure without an external field and the soliton lattice under an applied field. By applying this approach to Cr_1/3NbS₂ and Cr_1/3TaS₂, we have successfully predicted their helical period, helix wave vector, and critical field, in excellent agreement with experimental measurements, and resolves the long-standing debate about the relative strength of intralayer and interlayer exchange interactions. This approach can be generalized to other chiral helimagnets.