Quantum cascade of correlated phases in trigonally warped bilayer graphene

Seiler, A.; Geisenhof, Fabian R.; Winterer, Felix; Watanabe, Kenji; Taniguchi, Takashi; Xu, Tianyi; Zhang, Fan; Weitz, R. Thomas

doi:10.1038/s41586-022-04937-1

Cited by 67 publications

(32 citation statements)

References 39 publications

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“…How can one fabricate noninvasive contacts in suspended devices beyond the existing four-terminal ones? How does the electric field disorder impact the thermal proliferation of spontaneous DWs in suspended devices? How does the electric field disorder address the interplay between trigonal warping and Coulomb interaction and the resulting cascade of correlated phases, including fractional metals ,, and Wigner crystals? Finally, we note that the existence of electric field disorder should be universal to all 2D materials, and its unique impacts await exploration.…”

Section: Discussionmentioning

confidence: 97%

“…42 How does the electric field disorder impact the thermal proliferation of spontaneous DWs 26 in suspended devices? How does the electric field disorder address the interplay between trigonal warping and Coulomb interaction and the resulting cascade of correlated phases, including fractional metals 13,43,44 and Wigner crystals? 13 Finally, we note that the existence of electric field disorder should be universal to all 2D materials, and its unique impacts await exploration.…”

Section: ■ Outlookmentioning

confidence: 99%

“…Bernal bilayer graphene (BLG) has quadratic band touching at the charge neutrality point (CNP) and constant density of states in the single-particle spectrum, when trigonal warping is ignored. This implies that BLG is susceptible to exchange interaction-driven broken-symmetry states. − Such exotic states have been observed at finite magnetic field B ,− and, more intriguingly, also in its absence. ,− To clearly identify their underlying orders is, however, a long-standing challenge. States at vanishing magnetic field are especially intricate as they are degenerate in mean-field theory ,, despite their distinct spin-valley orders.…”

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confidence: 99%

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Impact of Electric Field Disorder on Broken-Symmetry States in Ultraclean Bilayer Graphene

et al. 2022

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Bilayer graphene (BLG) has multiple internal degrees of freedom and a constant density of states down to the charge neutrality point when trigonal warping is ignored. Consequently, it is susceptible to various competing ground states. However, a coherent experimental determination of the ground state has been challenging due to the interaction–disorder interplay. Here we present an extensive transport study in a series of dually gated freestanding BLG devices and identify the layer-antiferromagnet as the ground state with a continuous strength across all devices. This strength correlates with the width of the state in the electric field. We systematically identify electric-field disorderspatial variations in the interlayer potential differenceas the main source responsible for the observations. Our results pinpoint for the first time the importance of electric-field disorder on spontaneous symmetry breaking in BLG and solve a long-standing debate on its ground state. The electric-field disorder should be universal to all 2D materials.

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Section: Discussionmentioning

confidence: 97%

Section: ■ Outlookmentioning

confidence: 99%

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confidence: 99%

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Impact of Electric Field Disorder on Broken-Symmetry States in Ultraclean Bilayer Graphene

et al. 2022

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“…Recent advances have led to the observation of many fractional states and transitions between them. This means that we have at our disposal a physical system where we can tune parameters affecting the fractional quantum Hall physics [19][20][21][22][23][24][25][26][27] .…”

Section: Introductionmentioning

confidence: 99%

Competing Laughlin state and Wigner crystal in bilayer graphene

Le¹,

Jolicœur²

2022

Preprint

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We study the fractional quantum Hall effect in the central Landau level of bilayer graphene. By tuning the external applied magnetic field and the electric bias between the two layers one can access a regime where there is a degeneracy between Landau levels with orbital characters corresponding to N=0 and N=1 Galilean Landau levels. While the Laughlin state is generically the ground state for filling ν = 1/3 we find that it can be destroyed and replaced by a Wigner crystal at the same filling factor by tuning the bias and applied field. This competition does not take place at ν = 2/3 where the incompressible ground state remains stable. The possibility of electrically inducing the Wigner crystal state opens a new range of studies of this state of matter.

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“…Careful combinations of asymmetric potentials, doping levels, and small in-plane magnetic fields have recently shown intriguing many-body phases in Bernal stacked bilayer graphene with emerging superconductivity. 6,17,18 The epitaxially grown BLG on SiC(0001) represents an example of a Bernal stacked bilayer graphene 19,20 (see also Figure S1 and discussion therein). Negative charge transfer from the pristine interface of silicon-terminated SiC to the carbon buffer layer (BL) causes small, asymmetric doping between the top two graphene layers.…”

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confidence: 99%

Breaking of Inversion Symmetry and Interlayer Electronic Coupling in Bilayer Graphene Heterostructure by Structural Implementation of High Electric Displacement Fields

Kolmer

Hall

et al. 2022

J. Phys. Chem. Lett.

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Controlling the interlayer coupling in two-dimensional (2D) materials generates novel electronic and topological phases. Its effective implementation is commonly done with a transverse electric field. However, phases generated by high displacement fields are elusive in this standard approach. Here, we introduce an exceptionally large displacement field by structural modification of a model system: AB-stacked bilayer graphene (BLG) on a SiC(0001) surface. We show that upon intercalation of gadolinium, electronic states in the top graphene layers exhibit a significant difference in the on-site potential energy, which effectively breaks the interlayer coupling between them. As a result, for energies close to the corresponding Dirac points, the BLG system behaves like two electronically isolated single graphene layers. This is proven by local scanning tunneling microscopy (STM)/spectroscopy, corroborated by density functional theory, tight binding, and multiprobe STM transport. The work presents metal intercalation as a promising approach for the synthesis of 2D graphene heterostructures with electronic phases generated by giant displacement fields.

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Quantum cascade of correlated phases in trigonally warped bilayer graphene

Cited by 67 publications

References 39 publications

Impact of Electric Field Disorder on Broken-Symmetry States in Ultraclean Bilayer Graphene

Impact of Electric Field Disorder on Broken-Symmetry States in Ultraclean Bilayer Graphene

Competing Laughlin state and Wigner crystal in bilayer graphene

Breaking of Inversion Symmetry and Interlayer Electronic Coupling in Bilayer Graphene Heterostructure by Structural Implementation of High Electric Displacement Fields

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