Dirac Fermion Cloning, Moiré Flat Bands, and Magic Lattice Constants in Epitaxial Monolayer Graphene

Qiangsheng Lu; Congcong Le; Xiaoqian Zhang; Jacob Cook; Xiaoqing He; Mohammad Zarenia; Mitchel Vaninger; Paul F. Miceli; David J. Singh; Chang Liu; Hailang Qin; Tai Chang Chiang; Ching Kai Chiu; Giovanni Vignale; Guang Bian

doi:10.1002/adma.202200625

Dirac Fermion Cloning, Moiré Flat Bands, and Magic Lattice Constants in Epitaxial Monolayer Graphene

Qiangsheng Lu, Congcong Le, Xiaoqian Zhang, Jacob Cook, Xiaoqing He, Mohammad Zarenia, Mitchel Vaninger, Paul F. Miceli, David J. Singh, Chang Liu, Hailang Qin, Tai Chang Chiang, Ching Kai Chiu, Giovanni Vignale, Guang Bian

Research output: Contribution to journal › Article › peer-review

13 Scopus citations

Abstract

Tuning interactions between Dirac states in graphene has attracted enormous interest because it can modify the electronic spectrum of the 2D material, enhance electron correlations, and give rise to novel condensed-matter phases such as superconductors, Mott insulators, Wigner crystals, and quantum anomalous Hall insulators. Previous works predominantly focus on the flat band dispersion of coupled Dirac states from different twisted graphene layers. In this work, a new route to realizing flat band physics in monolayer graphene under a periodic modulation from substrates is proposed. Graphene/SiC heterostructure is taken as a prototypical example and it is demonstrated experimentally that the substrate modulation leads to Dirac fermion cloning and, consequently, the proximity of the two Dirac cones of monolayer graphene in momentum space. Theoretical modeling captures the cloning mechanism of the Dirac states and indicates that moiré flat bands can emerge at certain magic lattice constants of the substrate, specifically when the period of modulation becomes nearly commensurate with the (Formula presented.) supercell of graphene. The results show that epitaxial single monolayer graphene on suitable substrates is a promising platform for exploring exotic many-body quantum phases arising from interactions between Dirac electrons.

Original language	English
Article number	2200625
Journal	Advanced Materials
Volume	34
Issue number	26
DOIs	https://doi.org/10.1002/adma.202200625
State	Published - Jul 1 2022
Externally published	Yes

Funding

Q.L. and C.L. contributed equally to this work. G.B. was supported by the US National Science Foundation under Grant No. NSF DMR-1809160. T.-C.C. was supported by the U.S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences, Division of Materials Science and Engineering, under Grant No. DE-FG02-07ER46383. G.V. was supported by the US Department of Energy (Office of Science) under Grant No. DE-FG02-05ER46203. D.J.S. was supported by the U.S. Department of Energy, Basic Energy Sciences, Award DE-SC0019114. Note: Expressions for q2 and q3 in paragraph 4 of Section 3 were corrected on July 1, 2022, after initial publication online. Q.L. and C.L. contributed equally to this work. G.B. was supported by the US National Science Foundation under Grant No. NSF DMR‐1809160. T.‐C.C. was supported by the U.S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences, Division of Materials Science and Engineering, under Grant No. DE‐FG02‐07ER46383. G.V. was supported by the US Department of Energy (Office of Science) under Grant No. DE‐FG02‐05ER46203. D.J.S. was supported by the U.S. Department of Energy, Basic Energy Sciences, Award DE‐SC0019114.

Keywords

Dirac fermions
epitaxial monolayers
flat bands
graphene
moiré patterns

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10.1002/adma.202200625

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title = "Dirac Fermion Cloning, Moir{\'e} Flat Bands, and Magic Lattice Constants in Epitaxial Monolayer Graphene",

abstract = "Tuning interactions between Dirac states in graphene has attracted enormous interest because it can modify the electronic spectrum of the 2D material, enhance electron correlations, and give rise to novel condensed-matter phases such as superconductors, Mott insulators, Wigner crystals, and quantum anomalous Hall insulators. Previous works predominantly focus on the flat band dispersion of coupled Dirac states from different twisted graphene layers. In this work, a new route to realizing flat band physics in monolayer graphene under a periodic modulation from substrates is proposed. Graphene/SiC heterostructure is taken as a prototypical example and it is demonstrated experimentally that the substrate modulation leads to Dirac fermion cloning and, consequently, the proximity of the two Dirac cones of monolayer graphene in momentum space. Theoretical modeling captures the cloning mechanism of the Dirac states and indicates that moir{\'e} flat bands can emerge at certain magic lattice constants of the substrate, specifically when the period of modulation becomes nearly commensurate with the (Formula presented.) supercell of graphene. The results show that epitaxial single monolayer graphene on suitable substrates is a promising platform for exploring exotic many-body quantum phases arising from interactions between Dirac electrons.",

keywords = "Dirac fermions, epitaxial monolayers, flat bands, graphene, moir{\'e} patterns",

author = "Qiangsheng Lu and Congcong Le and Xiaoqian Zhang and Jacob Cook and Xiaoqing He and Mohammad Zarenia and Mitchel Vaninger and Miceli, \{Paul F.\} and Singh, \{David J.\} and Chang Liu and Hailang Qin and Chiang, \{Tai Chang\} and Chiu, \{Ching Kai\} and Giovanni Vignale and Guang Bian",

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doi = "10.1002/adma.202200625",

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T1 - Dirac Fermion Cloning, Moiré Flat Bands, and Magic Lattice Constants in Epitaxial Monolayer Graphene

AU - Lu, Qiangsheng

AU - Le, Congcong

AU - Zhang, Xiaoqian

AU - Cook, Jacob

AU - He, Xiaoqing

AU - Zarenia, Mohammad

AU - Vaninger, Mitchel

AU - Miceli, Paul F.

AU - Singh, David J.

AU - Liu, Chang

AU - Qin, Hailang

AU - Chiang, Tai Chang

AU - Chiu, Ching Kai

AU - Vignale, Giovanni

AU - Bian, Guang

PY - 2022/7/1

Y1 - 2022/7/1

N2 - Tuning interactions between Dirac states in graphene has attracted enormous interest because it can modify the electronic spectrum of the 2D material, enhance electron correlations, and give rise to novel condensed-matter phases such as superconductors, Mott insulators, Wigner crystals, and quantum anomalous Hall insulators. Previous works predominantly focus on the flat band dispersion of coupled Dirac states from different twisted graphene layers. In this work, a new route to realizing flat band physics in monolayer graphene under a periodic modulation from substrates is proposed. Graphene/SiC heterostructure is taken as a prototypical example and it is demonstrated experimentally that the substrate modulation leads to Dirac fermion cloning and, consequently, the proximity of the two Dirac cones of monolayer graphene in momentum space. Theoretical modeling captures the cloning mechanism of the Dirac states and indicates that moiré flat bands can emerge at certain magic lattice constants of the substrate, specifically when the period of modulation becomes nearly commensurate with the (Formula presented.) supercell of graphene. The results show that epitaxial single monolayer graphene on suitable substrates is a promising platform for exploring exotic many-body quantum phases arising from interactions between Dirac electrons.

AB - Tuning interactions between Dirac states in graphene has attracted enormous interest because it can modify the electronic spectrum of the 2D material, enhance electron correlations, and give rise to novel condensed-matter phases such as superconductors, Mott insulators, Wigner crystals, and quantum anomalous Hall insulators. Previous works predominantly focus on the flat band dispersion of coupled Dirac states from different twisted graphene layers. In this work, a new route to realizing flat band physics in monolayer graphene under a periodic modulation from substrates is proposed. Graphene/SiC heterostructure is taken as a prototypical example and it is demonstrated experimentally that the substrate modulation leads to Dirac fermion cloning and, consequently, the proximity of the two Dirac cones of monolayer graphene in momentum space. Theoretical modeling captures the cloning mechanism of the Dirac states and indicates that moiré flat bands can emerge at certain magic lattice constants of the substrate, specifically when the period of modulation becomes nearly commensurate with the (Formula presented.) supercell of graphene. The results show that epitaxial single monolayer graphene on suitable substrates is a promising platform for exploring exotic many-body quantum phases arising from interactions between Dirac electrons.

KW - Dirac fermions

KW - epitaxial monolayers

KW - flat bands

KW - graphene

KW - moiré patterns

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DO - 10.1002/adma.202200625

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Dirac Fermion Cloning, Moiré Flat Bands, and Magic Lattice Constants in Epitaxial Monolayer Graphene

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