Whirling interlayer fields as a source of stable topological order in moir\'e CrI3

Abstract

The moir\'e engineering of two-dimensional magnets opens unprecedented opportunities to design novel magnetic states with promises for spintronic device applications. The possibility of stabilizing skyrmions in these materials without chiral spin-orbit couplings or dipolar interactions is yet to be explored. Here, we investigate the formation and control of ground state topological spin textures (TSTs) in moir\'e CrI3 using stochastic Landau-Lifshitz-Gilbert simulations. We unveil the emergence of interlayer vortex and antivortex Heisenberg exchange fields, stabilizing spontaneous and field-assisted ground state TSTs with various topologies. The developed study accounts for the full bilayer spin dynamics, thermal fluctuations, and intrinsic spin-orbit couplings. By examining the effect of the Kitaev interaction and the next nearest-neighbor Dzyaloshinskii-Moriya interaction, we propose the latter as the unique spin-orbit coupling mechanism compatible with experiments on monolayer and twisted CrI3. Our findings contribute to the current knowledge about moir\'e skyrmionics and uncover the nature of spin-orbit coupling in CrI3.