Multiple Topological Phases with Electronic Correlation in Intrinsic Ferromagnetic Semimetal VI3 Monolayer

Abstract 2D topological materials with magnetic ordering have become hot topics due to their nontrivial band topology and quantum states. In this work, the second‐order topological states and evolution of linear band crossing are successfully predicted utilizing the effective k· p and tight binding models in the intrinsic ferromagnetic VI 3 monolayer under various effective Hubble interaction U eff . Upon inclusion of spin orbit coupling, a small bandgap (E g ‐1) of 12.7 meV is opened with a Chern invariant C = −1 at U eff = 0 eV. The E g ‐1 undergoes a transition from the non‐trivial state to trivial state at U eff = 0.80 eV, accompanied by the appearance of Dirac cone. Remarkably, the increase of U eff causes the band inversion and adjustment of crystal symmetry, resulting in two unreported coexisting topological bandgaps (E g ‐2 and E g ‐3). Furthermore, a gapless node‐loop appears at U eff = 1.06 eV and disappears at U eff = 1.09 eV around Γ point. Moreover, for the first time, the existence of second‐order topological states with quantized corner fractional charges (e/3) is also observed in the VI 3 monolayer at U eff ≥0.96 eV. These results make the VI 3 monolayer a compelling candidate for exploring topological devices.