Moiré-diamond formed via interlayer covalent transition in twisted multilayer graphene under compression

Abstract

Moiré lattice reconstruction and interlayer covalent transition in twisted multilayer graphene under uniaxial compression is investigated by density functional theory (DFT). Results show that the Moiré superlattice undergoes local rotational reconstruction amidst in-plane anisotropic strain induced by perpendicular pressure, coupled with shear effects at Moiré interference regions, prompting interlayer charge redistribution, which triggers a covalent bonding transition and forms a sp³ hybridized phase with Moiré periodicity, Moiré-diamond (m-dia). The m-dia exhibits a modulus, comparable to diamond, displays anisotropic characteristics, theoretical hardness up to 90.6 GPa, with tensile strength reaching 88.5 GPa. Meanwhile, large-scale molecular dynamics simulations reveal the coexistence of brittleness and ductility, attributed to pre-existing stress concentrated at Moiré periodic boundaries and the propagation of localized structural collapse. Evaluation of electrical properties confirms m-dia as a semiconductor, boasting an indirect bandgap of 5.44 eV (HSE06). These findings redefine the mechanical and electrostatic potential of Moiré-engineered superlattices, offering insight into how twist and pressure drive novel lattice architectures and functional properties in carbon systems.