Elastic screening of pseudo gauge fields in graphene

Straining a graphene lattice generates a pseudo-vector potential, which, for specific strain configurations, gives rise to a pseudo-magnetic field (PMF). Analogous to an externally applied magnetic field, this results in the formation of pseudo-Landau levels and related phenomena. Traditionally, the PMF has been derived in the low-strain limit using linear elasticity theory, which only accounts for acoustic deformations of the lattice. However, using molecular dynamics simulations in combination with large-scale tight-binding calculations we show that optical displacements, i.e., the relative motion of different sublattices, contribute to the PMF on the same order of magnitude as the acoustic component. We demonstrate this effect in two systems: twisted bilayer graphene and corrugated monolayer graphene. In both cases, the optical field effectively screens the PMF, leading to a significant reduction in its overall magnitude. This has a profound impact on the electronic properties, and has important implications for straintronics applications.