  Quantum anomalous Hall (QAH) insulators exhibit chiral edge channels
characterized by vanishing longitudinal conductance and quantized Hall
conductance of Ce2/h, wherein the Chern number C is an integer equal to the
number of the parallel chiral edge channels. These chiral edge channels conduct
dissipationless transport in QAH insulators, making them pivotal for
applications in low-consumption electronics and topological quantum computing.
While the QAH effect with multiple chiral edge channels (i.e., C >1) has been
demonstrated in multilayers consisting of magnetic topological insulators and
normal insulators, the channel number remains fixed for a given sample. Here,
we unveil the tunability of the number of chiral edge channels within a single
QAH insulator device. By tuning the magnetization of individual layers within
the multilayer system, Chern insulating states with different Chern numbers are
unveiled. The tunable Chern number was corroborated by our theoretical
calculations. Furthermore, we conducted layer-dependent calculations to
elucidate the contribution of the Chern number from different layers in the
multilayer. Our findings demonstrate an extra degree of freedom in manipulating
the chiral edge channels in QAH insulators. This newfound tunability offers
extra dimension for the implementation of the QAH-based multi-channel
dissipationless transport.
