Strain-programmable exciton diffusion in moir\'e heterostructures
Moir\'e superlattices in van der Waals heterostructures have recently gained significant attention as an intriguing platform for studying correlated electronic systems and exotic excitonic properties. Previous reports, however, focused on creating and modulating moir\'e heterostructures through interlayer twisting or lattice constant mismatches, limiting controls on symmetry of heterostructures. In this work, we show that strain significantly alters the geometry of moir\'e superlattices by breaking the C3 rotational symmetry. We realize strain-induced moir\'e superlattices by intentionally regulating interlayer strain in WSe2-MoSe2 heterostructures, which is manifested by linearly polarized interlayer exciton emission coupled to the strain direction. Furthermore, interlayer exciton diffusion was preferentially guided along the stretched moir\'e superlattice orientations over a wide spatial range, reflecting the strain-modified moir\'e potentials. Our work highlights strain tuning as a versatile tool for designing moir\'e superlattices and programming excitonic transport, which opens pathways for van der Waals logic and information processing devices.