Kekulé spirals and charge transfer cascades in twisted symmetric trilayer graphene

Fuente: arXiv
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Main Authors: Wang, Ziwei, Kwan, Yves H., Wagner, Glenn, Bultinck, Nick, Simon, Steven H., Parameswaran, S. A.
Format: Preprint
Published: 2023
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_version_ 1866915874641805312
author Wang, Ziwei
Kwan, Yves H.
Wagner, Glenn
Bultinck, Nick
Simon, Steven H.
Parameswaran, S. A.
author_facet Wang, Ziwei
Kwan, Yves H.
Wagner, Glenn
Bultinck, Nick
Simon, Steven H.
Parameswaran, S. A.
contents We study the phase diagram of magic-angle twisted symmetric trilayer graphene in the presence of uniaxial heterostrain and interlayer displacement field. For experimentally reasonable strain, our mean-field analysis finds robust Kekulé spiral order whose doping-dependent ordering vector is incommensurate with the moiré superlattice, consistent with recent scanning tunneling microscopy experiments, and paralleling the behaviour of closely-related twisted bilayer graphene (TBG) systems. Strikingly, we identify a new possibility absent in TBG: the existence of $\textit{commensurate}$ Kekulé spiral order even at zero strain for experimentally realistic values of the interlayer potential in a trilayer. Our studies also reveal a complex pattern of charge transfer between weakly- and strongly-dispersive bands in strained trilayer samples as the density is tuned by electrostatic gating, that can be understood intuitively in terms of the `cascades' in the compressibility of magic-angle TBG.
format Preprint
id arxiv_https___arxiv_org_abs_2310_16094
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Kekulé spirals and charge transfer cascades in twisted symmetric trilayer graphene
Wang, Ziwei
Kwan, Yves H.
Wagner, Glenn
Bultinck, Nick
Simon, Steven H.
Parameswaran, S. A.
Strongly Correlated Electrons
Mesoscale and Nanoscale Physics
We study the phase diagram of magic-angle twisted symmetric trilayer graphene in the presence of uniaxial heterostrain and interlayer displacement field. For experimentally reasonable strain, our mean-field analysis finds robust Kekulé spiral order whose doping-dependent ordering vector is incommensurate with the moiré superlattice, consistent with recent scanning tunneling microscopy experiments, and paralleling the behaviour of closely-related twisted bilayer graphene (TBG) systems. Strikingly, we identify a new possibility absent in TBG: the existence of $\textit{commensurate}$ Kekulé spiral order even at zero strain for experimentally realistic values of the interlayer potential in a trilayer. Our studies also reveal a complex pattern of charge transfer between weakly- and strongly-dispersive bands in strained trilayer samples as the density is tuned by electrostatic gating, that can be understood intuitively in terms of the `cascades' in the compressibility of magic-angle TBG.
title Kekulé spirals and charge transfer cascades in twisted symmetric trilayer graphene
topic Strongly Correlated Electrons
Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2310.16094