Gauge field induced by ripples in graphene

Gauge fields, ripples and wrinkles in graphene layers

We analyze elastic deformations of graphene sheets which lead to effective gauge fields acting on the charge carriers. Corrugations in the substrate induce stresses, which, in turn, can give rise to mechanical instabilities and the formation of wrinkles. Similar effects may take place in suspended graphene samples under tension.

Minimal conductivity of rippled graphene with topological disorder

We study the transport properties of a neutral graphene sheet with curved regions induced or stabilized by topological defects. The proposed model gives rise to Dirac fermions in a random magnetic field and in the random space dependent Fermi velocity induced by the curvature. This last term leads to singular long range correlated disorder with special characteristics. The Drude minimal conductivity at zero energy is found to be inversely proportional to the density of topological disorder, a signature of diffusive behavior.

Quantum Hall plateau transition in graphene with spatially correlated random hopping

We investigate how the criticality of the quantum Hall plateau transition in disordered graphene differs from those in the ordinary quantum Hall systems, based on the honeycomb lattice with ripples modeled as random hoppings. The criticality of the graphene-specific n=0 Landau level is found to change dramatically to an anomalous, almost exact fixed point as soon as we make the random hopping spatially correlated over a few bond lengths. We attribute this to the preserved chiral symmetry and suppressed scattering between K and K' points in the Brillouin zone. The results suggest that a fixed p…

Rippling and crumpling in disordered free-standing graphene

Graphene is a famous realization of elastic crystalline 2D membrane. Thermal fluctuations of a 2D membrane tend to destroy the long-range order in the system. Such fluctuations are stabilized by strong anharmonicity effects, which preserve thermodynamic stability. The anharmonic effects demonstrate critical behaviour on scales larger than the Ginzburg scale. In particular, clean suspended flake of graphene shows a power-law increase of the bending rigidity with the system size, $\varkappa\propto L^η,$ due to anharmonic interaction between in-plane and out-of-plane (flexural) phonon modes. We d…

Effect of disorder on the ground-state properties of graphene

We calculate the ground-state energy of Dirac electrons in graphene in the presence of disorder. We take randomly distributed charged impurities at a fixed distance from the graphene sheet and surface fluctuations (ripples) as the main scattering mechanisms. Mode-coupling approach to scattering rate and random-phase approximation for ground-state energy incorporating the many-body interactions and the disorder effects yields good agreement with experimental inverse compressibility.

缺陷诱导石墨烯中的涟漪从动态到静态的相变

Defects induce phase transition from dynamic to static rippling in graphene

该研究利用机器学习驱动的分子动力学模拟，发现石墨烯中缺陷浓度超过临界值时会发生从动态涟漪到静态涟漪的相变，揭示了缺陷间弹性相互作用驱动该相变的统一原理，为设计具有定制涟漪动力学的二维器件及新型无序基催化与界面材料奠定基础。