Whirling interlayer fields as a source of stable topological order in moiré CrI3

Abstract

The moiré 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 moiré $${Cr}{I}_{3}$$ C r I 3 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 $${Cr}{I}_{3}$$ C r I 3 . Our findings contribute to the current knowledge about moiré skyrmionics and uncover the nature of spin-orbit coupling in $${Cr}{I}_{3}$$ C r I 3 .

Emergence of Stable Meron Quartets in Twisted Magnets

“…Consequently, the interlayer exchange coupling exhibits the coexistence of AFM and FM interactions in the moirésuperlattice accommodating various local stacking patterns (Figure 2a). [20][21][22][23][24][25]34 We illustrate this behavior in Figure 2b through the map of the local interlayer exchange energy J i ⊥ = ∑ j J ij ⊥ computed in an FM configuration S i l = Sz. 20,22,24,34 Specifically, in the monoclinic stacking region (red patches), J i ⊥ exhibits AFM character (J i ⊥ > 0), indicating a tendency for the spins in the top and bottom layers to align antiparallel to each other.…”

“…[20][21][22][23][24][25]34 We illustrate this behavior in Figure 2b through the map of the local interlayer exchange energy J i ⊥ = ∑ j J ij ⊥ computed in an FM configuration S i l = Sz. 20,22,24,34 Specifically, in the monoclinic stacking region (red patches), J i ⊥ exhibits AFM character (J i ⊥ > 0), indicating a tendency for the spins in the top and bottom layers to align antiparallel to each other. Conversely, in the other stacking regions, J i ⊥ exhibits FM character (J i ⊥ < 0), signifying a preference for parallel alignment.…”

Non-coplanar helimagnetism in the layered van-der-Waals metal DyTe3

“…Most appealingly, DyTe 3 is a potential platform for spin-Moiré engineering in solids, where complex magnetic textures can be designed by combining and twisting two or more helimagnetic sheets. Here, a plethora of noncoplanar spin textures can be engineered at will [6,47], while highly conducting tellurium square net channels may serve as a test bed for of emergent electromagnetism in a tightly controlled setting [48,49]…”

Magnetic Skyrmion Lattices in a Novel 2D‐Twisted Bilayer Magnet

“…[ 23–25 ] Theoretical studies have predicted that it also depends on the stacking structure, [ 26–29 ] and a twisting may bring periodic magnetization domains with complex spin texture; [ 30–32 ] additional Dzyaloshinskii–Moriya (DM) interactions may further stabilize various magnetic skyrmions. [ 33–36 ] Rich phase diagrams with noncollinear spin configurations were obtained. [ 37,38 ] Compared with magnetic skyrmions in alloys, [ 39–42 ] the magnetic skyrmions in TBCIs are much thinner, which reach the 2D limit and open up the field of spintwistronics.…”