Strain modulated Chiral Magnetic Structures in Two-Dimensional Janus NiIX (X = Br, Cl)

Chiral magnetic structures, such as spiral phases and magnetic skyrmions, are promising for future spintronic application. Modulating these structures is of fundamental importance for related devices design. In this study, using first-principles calculations and atomistic simulations, we demonstrate that chiral magnetic structures in two-dimensional Janus NiIX (X = Br, Cl) can be effectively modulated by biaxial strain. Specifically, a tensile strain of 5% can reduce critical magnetic field required to generate skyrmions to one order of magnitude lower than that of pristine NiIBr. For NiICl, both perpendicular magnetic anisotropy and Dzyaloshinskii-Moriya interaction (DMI) are strongly suppressed as the tensile strain increases, resulting in the emergence of anti-skyrmion when magnetic frustration dominates. Furthermore, this study also reveals the modulation of skyrmion helicity due to the competition between weak DMI and magnetic frustration. These findings reveal a powerful method in reducing the critical field and modulating chiral magnetic structures in Janus NiIX, which is helpful for skyrmion-related experiments and applications.