Skyrmionic states induced by local Dzyaloshinskii-Moriya interaction

Magnetic skyrmions, typically stabilized by the Dzyaloshinskii-Moriya interaction (DMI), are promising candidates as the information carriers for advanced spintronic applications. In conventional micromagnetic theory, formation and morphology of skyrmion are generally thought to be restricted by symmetries associated with specific point groups. Here, through symmetry analysis and first-principles-based spin Hamiltonian calculations, we demonstrate that even in systems with zero net DMI, local DMI contributions can result in energy gains that stabilize noncollinear skyrmionic states. Symmetry constraints on global DMI, for example, confirm that systems with ${D}_{3h}$ and ${D}_{3d}$ point group symmetries yield zero net DMI. We identify two two-dimensional magnets, ${\mathrm{Mn}}_{2}{\mathrm{AgTe}}_{4}$ and ${\mathrm{In}}_{2}{\mathrm{Cr}}_{2}{\mathrm{Te}}_{5}$, with ${D}_{3h}$ and ${D}_{3d}$ symmetries, respectively, where magnetic atoms exhibit $3m.$ site symmetry with their nearest neighbors. In these systems, local DMI stabilizes N\'eel-type skyrmions, forming a skyrmionic phase in ${\mathrm{Mn}}_{2}{\mathrm{AgTe}}_{4}$ and a metastable excitation state in ${\mathrm{In}}_{2}{\mathrm{Cr}}_{2}{\mathrm{Te}}_{5}$. This study expands the search for skyrmionic phases in materials with unconventional point group symmetries, enriching the landscape of skyrmionic systems.