Topological junctions in high-Chern-number quantum anomalous Hall systems

Quantum anomalous Hall effect (QAHE) is the real topological state without magnetic field that is robust against any perturbations, and is related to a bulk topological number $\mathcal{C}$, counting the number of chiral edge modes. Such chiral edge modes also exist at the magnetic domain walls between regions with different Chern numbers. Here, we systematically investigate the electronic properties of topological junctions formed at boundaries of QAHEs with different Chern numbers. We find that the number of chiral edge modes along the junction is determined by the difference of Chern numbers of adjacent regions, which can be understood from the coupling between counterpropagating channels along the junction. Finally, we show that the current partition of topological junctions can be flexibly manipulated by tuning the number of quantum anomalous Hall regions, Chern numbers, and the magnetization directions. Our work provides an ideal platform to design multichannel low-power devices for electronic circuits and switching applications.