Formation of a high-density skyrmion crystal in the monolayer semiconductor LiCrTe2 with tunable bands

Skyrmions, as unique wrapped spin textures, hold great potential for next-generation spintronic devices. Here, we reveal the emergence of nontrivial spin textures in the monolayer semiconductor LiCrTe2 through a combination of first-principles calculations and micromagnetic simulations, which evolve into a Néel-type skyrmion crystal (SkX) in response to external magnetic fields at finite temperatures. The monolayer can sustain a high density of skyrmions, reaching up to 0.018 skyrmions/nm2 with a diameter of 2.9 nm, which surpasses values in previous reports for semiconductor layers. The synergistic effect of temperature and magnetic field on the formation of a SkX has been identified. Furthermore, we observe an inverse relationship between the electronic band gap and the skyrmion size in the SkX. Notably, the band gap closes and reverses as the size of skyrmions increases when the monolayer is compressed by -3% in-plane biaxial strain, highlighting the tunable interplay between real-space and reciprocal-space spin textures. Our results shed light on the evolution of a SkX in a semiconducting monolayer and demonstrate the transition of topological and electronic properties upon the generation of a SkX, providing valuable insights for experimental realization and future spintronic applications.