Topological Flat Bands in Strained Graphene: Substrate Engineering and Optical Control

Abstract

The discovery of correlated phases in twisted moireś uperlattices accelerated the search for low-dimensional materials with exotic properties. A promising approach uses engineered substrates to strain the material. However, designing substrates for tailored properties is hindered by the incomplete understanding of the relationship between the substrate's shapes and the electronic properties of the deposited materials. By analyzing effective models of graphene under periodic deformations with generic crystalline profiles, we identify strong C 2z symmetry breaking as the critical substrate geometric feature for emerging energy gaps and quasi-flat bands. We find continuous strain profiles producing connected pseudomagnetic field landscapes are important for band topology. We show that the resultant electronic and topological properties from a substrate can be controlled with circularly polarized light, which also offers unique signatures for identifying the band topology imprinted by strain. Our results can guide experiments on strain engineering for exploring interesting transport and topological phenomena.

Roses in the nonperturbative current response of artificial crystals

“…Here, we consider a substrate-induced buckling transition that gives rise to a periodic height profile with symmetry. In the first-star approximation, the height profile is given by with , where the phase controls the shape of the profile ( 8 , 30 – 32 ). Experimentally, can be tuned by designing different artificial substrates.…”

Flat bands without twists: periodic holey graphene

“…For this reason, alternative systems are currently being explored to preserve flat bands without relying solely on the rotation angle. Examples of these systems include graphene subjected to mechanical deformations [21][22][23][24][25][26][27][28][29] , multilayer graphene twisted (MTLG) under pressure [30][31][32][33][34], cyclicgraphyne, cyclicgraphdiyne [35] and holey graphene (HG) [36][37][38][39], where the theoretical possibility of chiral superconductivity emergence has been demonstrated [40].…”

Wetting and strain engineering of 2D materials on nanopatterned substrates

“…27 These properties play an important role in shaping the electronic and optoelectronic performance of 2D materials. 28–33 The adhesion energies of 2D materials to substrates, for example, have been reported in various materials: 6 to 28 meV Å −2 for graphene on silicon oxide, 6,34–37 9.4 meV Å −2 for graphene on silicon, 38,39 1.12 meV Å −2 for MoS 2 on PMDS, 40 6.3 meV Å −2 for MoS 2 on Al 2 O 3 , 41 and 5 meV Å −2 for MoS 2 on SiO 2 . 41 Studies on the folding behavior of 2D materials, 42 and investigations of heterostructures involving 2D materials, 43 provide valuable information on their mechanical characteristics.…”