First-principles prediction of intrinsic ferrovalley properties in Janus rare-earth PrXY (X ≠ Y = Cl, Br, I) monolayers†

In this work, using first-principles calculations, we predict a promising class of two-dimensional ferromagnetic semiconductors, namely Janus PrXY (X ≠ Y = Cl, Br, I) monolayers. Through first-principles calculations, we found that PrXY monolayers have excellent dynamic and thermal stability, and their band structures, influenced by magnetic exchange and spin–orbital coupling, exhibit significant valley polarization. Between K and −K valleys, the Berry curvature values are opposite to each other, resulting in the anomalous valley Hall effect. In addition, applying moderate biaxial strain can further enhance their magnetic anisotropy energy and valley polarization. These findings do not only emphasize the importance of strain in regulating spin and valley characteristics, but also provide new possibilities for the application of ferromagnetic semiconducting materials in spintronic and valleytronic devices.