Topological hidden phase transition in honeycomb bilayers with a high Chern number

Topological phases have garnered considerable attention due to their robust quantum transport properties. However, observing the topological phase transition within valence bands seems to be elusive from the perspective of quantum transport. Here, the authors uncover this ``topological hidden phase transition'' in a composite honeycomb bilayer. They demonstrate that the emergence of robust ``half-antichiral'' edge states with the bi-conductance plateau is a fingerprint of the phenomenon in which the Chern number of the valence bands undergoes a transition from $C$=\ifmmode\pm\else\textpm\fi{}(1+1) to $C$=\ifmmode\pm\else\textpm\fi{}(2+0).