Electric Field Control Of Moiré Skyrmion Phases in Twisted Multiferroic NiI2 Bilayers

Abstract

Twisted magnetic van der Waals materials provide a flexible platform to engineer unconventional magnetism. Here we demonstrate the emergence of electrically tunable topological moiré magnetism in twisted bilayers of the spin-spiral multiferroic NiI2. We establish a rich phase diagram featuring uniform spiral phases, a variety of kπ-skyrmion lattices, and nematic spin textures ordered at the moiré scale. The emergence of these phases is driven by the local stacking and the resulting moiré modulated frustration. Notably, when the spin-spiral wavelength is commensurate with the moiré length scale by an integer k, multiwalled skyrmions become pinned to the moiré pattern. We show that the strong magnetoelectric coupling displayed by the moiré multiferroic allows electric control of the kπ-skyrmion lattices by an out-of-plane electric field. Our results establish a highly tunable platform for skyrmionics based on twisted van der Waals multiferroics, potentially enabling a new generation of ultrathin topologically protected spintronic devices.