High harmonic generation in graphene-boron nitride heterostructures
van der Waals heterostructures formed by stacking various atomically thin crystals have been a powerful approach to explore designer material with nearly limitless new properties. Here we report nonperturbative high harmonic generation (HHG) in two-dimensional (2D) heterostructures combing graphene and hexagonal boron nitride (G/hBN). First-principles calculation results reveal that G/hBN bilayer extends the HHG properties of the constituent layers. Harmonic intensity can be significantly enhanced by several orders of magnitude by tuning the Berry curvature of G/hBN via pressure-controlled interlayer interaction. The result offers a new way to enhance HHG in graphene. It also demonstrates that van der Waals heterostructures and their novel degrees of freedom can be employed to control the HHG process and opens up more possibilities to manipulate strong-field ultrafast physical properties in such 2D materials.