Magnetic phase transition and valley splitting in Janus GdBrI bilayer

The successful synthesis of two-dimensional Janus MoSSe and the emergence of anomalous valley Hall effect in magnetic transition metal dihalides has propelled valleytronics. In this study, we investigated the influence of stacking order on bilayer Janus GdBrI using first-principles computational methods. The calculation results indicate that the interlayer coupling is highly dependent on the stacking order, enabling transition between ferromagnetic (FM) and antiferromagnetic (AFM) via lateral displacement. Interestingly, the FM-coupled systems exhibit bipolar magnetic semiconductor characteristics. Under the influence of spin–orbit coupling, the system undergoes valley splitting, and the non-zero valley-contrast Berry curvature can be observed. Additionally, the interlayer magnetic coupling of the system can also be tuned to switch between AFM and FM states through biaxial strain and charge doping. These intriguing findings provide theoretical insights for the design of spintronic devices.