Twist-angle sensitivity of electron correlations in moiré graphene bilayers

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Title: Twist-angle sensitivity of electron correlations in moiré graphene bilayers
Authors: Goodwin, ZAH
Corsetti, F
Mostofi, AA
Lischner, J
Item Type: Journal Article
Abstract: Motivated by the recent observation of correlated insulator states and unconventional superconductivity in twisted bilayer graphene, we study the dependence of electron correlations on the twist angle and reveal the existence of strong correlations over a narrow range of twist angles near the magic angle. Specifically, we determine the on-site and extended Hubbard parameters of the low-energy Wannier states using an atomistic quantum-mechanical approach. The ratio of the on-site Hubbard parameter and the width of the flat bands, which is an indicator of the strength of electron correlations, depends sensitively on the screening by the semiconducting substrate and the metallic gates. Including the effect of long-ranged Coulomb interactions significantly reduces electron correlations and explains the experimentally observed sensitivity of strong-correlation phenomena on twist angles.
Issue Date: 13-Sep-2019
Date of Acceptance: 13-Sep-2019
ISSN: 2469-9950
Publisher: American Physical Society (APS)
Journal / Book Title: Physical Review B
Volume: 100
Issue: 12
Copyright Statement: ©2019 American Physical Society
Sponsor/Funder: Engineering & Physical Science Research Council (EPSRC)
Engineering and Physical Sciences Research Council
Funder's Grant Number: EP/S025324/1
Publication Status: Published
Article Number: 121106
Online Publication Date: 2019-09-13
Appears in Collections:Materials
Faculty of Natural Sciences

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