Moiré pattern

About: Moiré pattern is a research topic. Over the lifetime, 1917 publications have been published within this topic receiving 27176 citations. The topic is also known as: moiré fringes & moire pattern.

Topological invariant and domain connectivity in moiré materials

Abstract: Recently, a moir\'e material has been proposed in which multiple domains of different topological phases appear in the moir\'e unit cell due to a large moir\'e modulation. Topological properties of such moir\'e materials may differ from those of the original untwisted layered material. In this paper, we study how the topological properties are determined in moir\'e materials with multiple topological domains. We show a correspondence between the topological invariant of moir\'e materials at the Fermi level and the topology of the domain structure in real space. We also find a bulk-edge correspondence that is compatible with a continuous change in the truncation condition, which is specific to moir\'e materials. We demonstrate these correspondences in the twisted Bernevig-Hughes-Zhang model that describes general ${\mathbb{Z}}_{2}$-indicated topological insulator phases, by tuning its domain structure in the moir\'e unit cell. The obtained result can only be used to determine the topology at the Fermi level in the charge-neutral condition, but it can be combined with the traditional Wilson loop analysis to determine topologies of other gaps around. These results give a feasible method to evaluate a topological invariant for all occupied bands of a moir\'e material and contribute to the design of topological moir\'e materials and devices.

Elastic properties of moiré lattices in epitaxial two-dimensional materials

Abstract: Unlike conventional two-dimensional (2D) semiconductor superlattices, moir\'{e} patterns in 2D materials are flexible and their electronic, magnetic, optical, and mechanical properties depend on their topography. Within a continuous+atomistic theory treating 2D materials as crystalline elastic membranes, we abandon the flat-membrane scenario usually assumed for these materials and address out-of-plane deformations. We confront our predictions to experimental analyses on model systems, epitaxial graphene, and MoS$_2$ on metals and reveal that compression/expansion and bending energies stored in the membrane can compete with adhesion energy, leading to a subtle moir\'{e} wavelength selection and the formation of wrinkles.

Patterned bilayer graphene as a tunable strongly correlated system

Abstract: Recent observations of superconductivity in moire graphene have led to an intense interest in that system, with subsequent studies revealing a more complex phase diagram including correlated insulators and ferromagnetic phases. Here we propose an alternate system, electrostatically patterned bilayer graphene, in which a supermodulation is induced via metallic gates rather than the moire effect. We show that, by varying either the gap or the modulation strength, bilayer graphene can be tuned into the strongly correlated regime. Further calculations show that this is not possible in monolayer graphene. We present a general technique for addressing Coulomb screening of the periodic potential and demonstrate that this system is experimentally feasible.

Study of Moire Measuring Techniques for Wind Tunnel Model Deformation

Abstract: : Moire pattern measurement techniques for measurement of changes in the shape of aerodynamic models during wind tunnel tests was investigated. Theoretical and experimental study resulted in a recommendation of a Moire system with a major variation. The grid is physically applied at the model surface. Images are recorded on film in two views for both the distorted and undistorted cases. These images are then processed to determine the position of the grids in the undistorted condition as well as the magnitude of the distortion suffered by the grids during the test.