Nano-polaritonics in twisted van der Waals heterostructures

Interlayer coupling in atomic van der Waals heterostructures plays a rather unique role in controlling their optical and electronic properties. The character of the interlayer coupling can be manipulated by a particular stacking arrangement of the proximal layers and by adjusting the orientation of the neighboring planes. The latter method is known to trigger the long-range periodic modulations referred to as twisted moiré superlattices. The presence of periodic moiré patterns enables further fine tuning of the electronic band structure and yielding rich insights into the electronic/optical phenomenon. This has been manifested in graphene/hexagonal boron nitride (G/hBN) moiré patterns, twisted bilayer graphene structures as well as twisted hBN crystals. Using nano-infrared optical microscopy we have experimentally studied the collective excitations in these twisted moiré structures. We analyzed these soliton networks and obtained the local electrodynamical characters based on the infrared active polaritonics at the nanoscale.