Influence of electronic correlation on the valley and topological properties of VSiGeP₄ monolayer

Valley is used as a new degree of freedom for information encoding and storage. In this work, the valley and topological properties of the VSiGeP₄ monolayer were studied by adjusting the U value based on first-principles calculations. The VSiGeP₄ monolayer remains in a ferromagnetic ground state regardless of the change in the U value. The magnetic anisotropy of the VSiGeP₄ monolayer is initially in-plane, and then turns out-of-plane with the increase in the U value. Moreover, a topological phase transition is observed in the present VSiGeP₄ monolayer with the increase in U value from 0 to 3 eV, i.e., the VSiGeP₄ monolayer behaves as a bipolar magnetic semiconductor, a ferrovalley semiconductor, a half-valley metal characteristic, and a quantum anomalous Hall state. The mechanism of the topological phase transition behavior of the VSiGeP₄ monolayer was analyzed. It was found that the variation in U values would change the strength of the electronic correlation effect, resulting in the valley and topological properties. In addition, carrier doping was studied to design a valleytronic device using this VSiGeP₄ monolayer. By doping 0.05 electrons per f.u., the VSiGeP₄ monolayer with a U value of 3 eV exhibits 100% spin polarization. This study indicates that the VSiGeP₄ monolayer has potential applications in spintronic, valleytronic, and topological electronic nanodevices.