Tuning moiré twist angles enhances tensile plasticity in bulk van der Waals crystals.

Moiré twisting breaks the inherent symmetry of crystal structures, providing a promising method for tuning emergent quantum phenomena and physical properties in layered materials. Here we demonstrate that moiré twisting can also be harnessed to effectively enhance the tensile plasticity of bulk layered van der Waals crystals. We show that interlayer moiré twisting, spanning a broad range of twist angles commensurate with the crystal's translational symmetry, can be controllably introduced through simple off-axis compression in ternary bulk layered van der Waals crystals. It facilitates efficient stress relaxation under mechanical loading with a further increase in the moiré twist angles and enables a substantial increase by up to 360% in room-temperature macroscopic tensile ductility, reaching 30% tensile strain along the a-b plane. Moreover, moiré twisting occurs only between layers and, thus, negligibly affects the in-plane electronic properties. By establishing tunable moiré twisting as an effective mechanism for plastic deformation, this work provides a broadly applicable strategy for enhancing tensile ductility in bulk layered materials.