  At the interface between two-dimensional materials with different topologies,
topologically protected one-dimensional states (also named as zero-line modes)
arise. Here, we focus on the quantum anomalous Hall effect based zero-line
modes formed at the interface between regimes with different Chern numbers. We
find that, these zero-line modes are chiral and unilaterally conductive due to
the breaking of time-reversal invariance. For a beam splitter consisting of two
intersecting zero lines, the chirality ensures that current can only be
injected from two of the four terminals. Our numerical results further show
that, in the absence of contact resistance, the (anti-)clockwise partitions of
currents from these two terminals are the same owing to the current
conservation, which effectively simplifies the partition laws. We find that the
partition is robust against relative shift of Fermi energy, but can be
effectively adjusted by tuning the relative magnetization strengths at
different regimes or relative angles between zero lines.
