Influence of electronic correlation on the valley and topological properties of VSiGeP 4 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 VSiGeP 4 monolayer were studied by adjusting the U value based on first-principles calculations. The VSiGeP 4 monolayer remains in a ferromagnetic ground state regardless of the change in the U value. The magnetic anisotropy of the VSiGeP 4 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 VSiGeP 4 monolayer with the increase in U value from 0 to 3 eV, i.e. , the VSiGeP 4 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 VSiGeP 4 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 VSiGeP 4 monolayer. By doping 0.05 electrons per f.u., the VSiGeP 4 monolayer with a U value of 3 eV exhibits 100% spin polarization. This study indicates that the VSiGeP 4 monolayer has potential applications in spintronic, valleytronic, and topological electronic nanodevices.