A mixed Weyl semimetal in a two-dimensional ferromagnetic BaCrSe 2 monolayer

Weyl semimetals (WSMs) are of significant fundamental and technological importance in topotronics. Despite the fact that numerous WSMs in three dimensions are achieved, the emergence of WSMs in two-dimensional (2D) ferromagnets remains elusive. Here, we put forward the 2D BaCrSe 2 monolayer with intrinsic ferromagnetic order and full spin polarization as a specific representative of WSMs via including the magnetization direction θ into the topological analysis. Remarkably, the mixed Weyl points pinned exactly at the Fermi level, and the nonzero topological charge Q = ±1 is indeed achieved through a closed surface that encompasses a distinct mixed Weyl point in phase space ( k x , k y , θ ). The presented results not only advance the general understanding of WSMs in 2D ferromagnets but also put forward potential applications in topotronics.