Generation of isolated flat bands with tunable numbers through Moiré engineering

Abstract

Unlike the spin-1/2 fermions, the Lieb and Dice lattices both host triply-degenerate low-energy excitations. Here, we discuss Moiré structures involving twisted bilayers of these lattices, which are shown to exhibit a tunable number of isolated flat bands near the Fermi level. These flat bands remain isolated from the high-energy bands even in the presence of small higher-order terms and chiral-symmetry-breaking interlayer tunneling. At small twist angles, thousands of flat bands can be generated to substantially amplify flat band physics. We demonstrate that these flat bands carry substantial quantum weight so that upon adding a BCS-type pairing potential, the associated superfluid weight would also be large, and the critical superconducting temperature would be tunable. Our study suggests a new pathway for flat-band engineering based on twisted bilayer Lieb and Dice lattices.

arXiv comment11 pages, 9 figures

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Cited by in corpus (5)

• General Electronic Structure Calculation Method for Twisted Systems
• Emergent topology of flat bands in a twisted bilayer $\alpha$-$T_3$ lattice
• Geometry-Driven Moiré Engineering in Twisted Bilayers of High-Pseudospin Fermions
• Enhanced Backgate Tunability on Interfacial Carrier Concentration in Ionic Liquid-Gated MoS2 Devices
• Quantum Geometry Driven Finite-Momentum Exciton Fluctuations in Flat-Band Systems