Critical role of device geometry for the phase diagram of twisted bilayer graphene
File(s)
Published version
Author(s)
Type
Journal Article
Abstract
The effective interaction between electrons in two-dimensional materials can be modified by their environment, enabling control of electronic correlations and phases. Here, we study the dependence of electronic correlations in twisted bilayer graphene (tBLG) on the separation to the metallic gate(s) in two device configurations. Using an atomistic tight-binding model, we determine the Hubbard parameters of the flat bands as a function of gate separation, taking into account the screening from the metallic gate(s), the dielectric spacer layers, and the tBLG itself. We determine the critical gate separation at which the Hubbard parameters become smaller than the critical value required for a transition from a correlated insulator state to a (semi)metallic phase. We show how this critical gate separation depends on twist angle, doping, and the device configuration. These calculations may help rationalize the reported differences between recent measurements of tBLG's phase diagram and suggest that correlated insulator states can be screened out in devices with thin dielectric layers.
Date Issued
2020-04-15
Date Acceptance
2020-03-10
Citation
Physical Review B: Condensed Matter and Materials Physics, 2020, 101 (16), pp.1-8
ISSN
1098-0121
Publisher
American Physical Society
Start Page
1
End Page
8
Journal / Book Title
Physical Review B: Condensed Matter and Materials Physics
Volume
101
Issue
16
Copyright Statement
©2020 American Physical Society
Sponsor
Engineering and Physical Sciences Research Council
Engineering & Physical Science Research Council (EPSRC)
Engineering and Physical Sciences Research Council
Identifier
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000525101900003&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
Grant Number
EP/L015579/1
EP/S025324/1
EPSRC (EP/L015579/1)
Subjects
Science & Technology
Technology
Physical Sciences
Materials Science, Multidisciplinary
Physics, Applied
Physics, Condensed Matter
Materials Science
Physics
MAGIC-ANGLE
ELECTRON CORRELATIONS
SUPERCONDUCTORS
Publication Status
Published
Article Number
ARTN 165110
Date Publish Online
2020-04-09