Substantial electronic correlation effects on the electronic properties in a Janus FeClF monolayer

Electronic correlation may have an essential influence on the electronic structure in some materials with special structures and localized orbital distribution. In this work, taking a Janus monolayer FeClF as concrete example, effects its are investigated by using generalized gradient approximation plus $U$ approach. For perpendicular magnetic anisotropy (PMA), increasing electron can induce ferrovalley (FV) to half-valley-metal (HVM) quantum anomalous Hall (QAH) HVM FV transitions. QAH state, there is unit Chern number chiral edge state connecting conduction valence bands. The at boundary of phase, whose carriers intrinsically 100% valley polarized. With in-plane anisotropy, no states prominent polarization observed. However, for both out-of-plane sign-reversible Berry curvature be observed $U$. It found that these phenomenons related change ${d}_{xy}/{d}_{{x}^{2}\ensuremath{-}{y}^{2}}$ ${d}_{{z}^{2}}$ distributions different magnetocrystalline directions. also energy Curie temperature strongly depend PMA, typical $U=2.5$ eV, splitting 109 meV, which switched reversing magnetization direction. When considering intrinsic easy axis changes from out plane $U$, critical value about 1.15 eV. shows states. analysis results readily extended other nine members $\mathrm{Fe}XY$ ($X/Y=\text{F}$, Cl, Br, I) due sharing same Fe-dominated low-energy correlations monolayer. Our work emphasizes importance determine exceptional phase