Twist degree of freedom activated by pressure-driven interlayer engineering in spiral WS₂.

Abstract

Precise twist-angle control in van der Waals (vdW) moiré superlattices enables twistronic tuning of interfacial responses and emergent quantum states, but it remains unclear how atomic registry in three-dimensional stacks is linked to interlayer coupling and whether it can produce an internal twist degree of freedom without external torque. Here, we show that, via interlayer engineering, screw-dislocation-driven multilayer spiral WS₂ exhibits a reversible pressure-induced rotation of second-harmonic-generation polar pattern that saturates near 1 GPa, corresponding to an effective average interlayer twist of 0.2° per layer. This compression-twist coupling arises from moiré defined hierarchy of stacking energies and the associated atomic reconstruction, which together generate a spontaneous rotational torque at a slipped, metastable interface and couple the twist angle to the interlayer spacing. Our findings establish twist-degree-of-freedom manipulation in vdW crystals, opening pathways to reshape correlation-driven behaviors in moiré-of-moiré architectures and to explore chiral elasticity beyond Cauchy continuum mechanics.