Topologically protected moire exciton at a twist-boundary in a van der Waals heterostructure

A twin boundary in one of the layers of a twisted van der Waals heterostructure separates regions with near opposite inter-layer twist angles. In a MoS2/WSe2 bilayer, the regions with R-h(h) and R-h(X) stacking registry that defined the sub-lattices of the moire honeycomb pattern would be mirror-reflected across such a twist boundary. In that case, we demonstrate that topologically protected chiral moire exciton states are confined at the twist boundary. These are one-dimensional and uni-directional excitons with opposite velocities for excitons composed by electronic states with opposite valley/spin character, enabling intrinsic, guided, and far reaching valley-polarized exciton currents.

Automated summary

In a twisted van der Waals heterostructure, a twin boundary separates regions with nearly opposite inter-layer twist angles. In a MoS2/WSe2 bilayer, topologically protected chiral moire exciton states are confined at the twist boundary, which are one-dimensional and uni-directional excitons composed of electronic states with opposite valley/spin character, enabling intrinsic, guided, and far-reaching valley-polarized exciton currents.