  We propose a generic scenario for metastability and excitation-induced
switching in layered materials. Focusing on a minimal bilayer stack, where each
layer consists of a honeycomb lattice with A and B sublattices, we map out the
energy landscape with respect to the relative sliding of the layers. The
sliding affects the interlayer hopping, which induces a splitting between
bonding and anti-bonding bands. When this splitting is large, the AA and AB
stacking configurations correspond to the global and secondary minima,
respectively, and these configurations are separated by a barrier against
layer-sliding. While chemical doping only flattens this barrier, strong
\emph{photodoping} from bonding to antibonding bands can transiently
destabilize the global minimum and induce a sliding motion toward the AB
stacked configuration, thereby switching from an equilibrium insulator to a
nearly gapless metastable phase. This hopping-driven effect is enhanced by
local repulsive interactions, which increase the gap and facilitate the
inter-layer sliding.
