Direct Determination of Torsion in Twisted Graphite and MoS₂ Interfaces.

Abstract

The design space of two-dimensional materials is undergoing significant expansion through the stacking of layers in non-equilibrium configurations. However, the lack of quantitative insights into twist dynamics impedes the development of such heterostructures. Herein, we utilize the lateral force sensitivity of an atomic force microscope cantilever and specially designed rotational bearing structures to measure the torque in graphite and MoS₂ interfaces. While the extracted torsional energies are virtually zero across all angular misfit configurations, commensurate interfaces of graphite and MoS₂ are characterized by values of 0.1533 and 0.6384 N-m/m², respectively. Furthermore, we measured the adhesion energies of graphite and MoS₂ to elucidate the interplay between twist and slide. The adhesion energy dominates over the torsional energy for the graphitic interface, suggesting a tendency to twist prior to superlubric sliding. Conversely, MoS₂ displays an increased torsional energy exceeding its adhesion energy. Consequently, our findings demonstrate a fundamental disparity between the sliding-to-twisting dynamics at MoS₂ and graphite interfaces.