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    Twisted bilayer graphene and twistronics

    Also known as magic-angle graphene, twistronics, moiré materials, MATBG

    Twisted bilayer graphene is two graphene sheets stacked with a small rotation; near a "magic angle" of about 1.1° it develops flat electronic bands and becomes a superconductor, as shown in 2018.[1] The approach, often called twistronics, has since produced zero-field fractional quantum Hall states in moiré materials, with new forms still being reported in 2026.[2][3][4]

    Editor reviewedUpdated Materials sciencePhysicsScience
    Key facts

    What it is

    Take two sheets of graphene, each one atom thick, stack them and rotate one slightly. The offset creates a larger repeating “moiré” pattern. A 2011 theory paper predicted that at “magic” twist angles of about one degree, the lowest electronic band of this structure becomes flat. Electrons in it would move very slowly, so their interactions with each other would dominate.[5]

    In 2018 experimenters confirmed the idea. Near 1.1°, twisted bilayer graphene showed ultra-flat bands and superconductivity up to 1.7 K, which could be switched on and off with an electric gate.[1] Its temperature-density phase diagram has superconducting domes like the cuprate high-temperature superconductors. That made it the first purely carbon-based 2D superconductor and a tunable model system for unconventional superconductivity.[6]

    How the field grew

    Twisting is a control knob that can be added to any stack of layered crystals: a “van der Waals heterostructure” assembled layer by layer.[7] The most striking results since 2023 concern quantum Hall states, in which conductance comes in exact steps fixed by topology.[8] Graphene had not shown the fractional version without a magnetic field before 2024.[3]

    • In 2023, researchers observed the fractional quantum anomalous Hall effect, with fractional steps and no magnetic field, in twisted bilayer MoTe2.[2]
    • A 2024 Nature paper reported integer and fractional versions in rhombohedral five-layer graphene aligned with hexagonal boron nitride, the first time in graphene without a magnetic field.[3]
    • On 15 July 2026 Nature published quantum anomalous Hall insulators with Chern numbers from 1 to 7, plus an exotic fractional state with C = 7/3, in a twisted stack of bilayer and four-layer graphene.[4]

    Why it matters

    Fractional states without a magnetic field open the way to studying charge fractionalisation and exotic “anyon” statistics, and topological phases are seen as candidates for future quantum computers (see topological-qubits).[2][9] Magic-angle graphene’s cuprate-like phase diagram also lets researchers tune a single device through the phases of an unconventional superconductor.[6]

    The limits are practical: the superconductivity appears only below about 1.7 K.[1] For the broader picture, see how 2D materials work.

    Insulator and superconductor in one

    The 2018 discovery came as two Nature papers from MIT and Harvard physicists, published on 5 March 2018. At the magic angle the two sheets stopped conducting, much like the exotic class of materials called Mott insulators. Adding small amounts of electrons with a voltage made the material superconduct on its own, with no contact with other superconducting metals.[10] Superconductivity appears at a relatively high temperature given how few charge carriers the material has. Its discoverers therefore placed it among the most strongly coupled superconductors known, close to the BCS-BEC crossover.[11]

    That combination is why the team leader called graphene a new platform for studying unconventional superconductivity. He also imagined a superconducting transistor that could be switched between superconducting and insulating states.[12] No such device is near production: the effect needs temperatures below about 1.7 K.[1] How conventional chips are made today is covered in how chips are made.

    Questions readers ask

    What is the magic angle in graphene?

    A twist of about 1.1° between two graphene layers, at which the electronic bands become extremely flat and superconductivity appears.[1][5]

    Is magic-angle graphene a high-temperature superconductor?

    No. It superconducts only up to about 1.7 K, but its phase diagram resembles that of the high-temperature cuprates, which makes it useful for studying them.[1][6]

    What is the fractional quantum anomalous Hall effect?

    Fractionally quantised Hall resistance that appears without an external magnetic field. It was observed in twisted MoTe2 in 2023 and in rhombohedral pentalayer graphene in 2024.[2][3]

    Sources

    Each numbered claim is a statement we checked against the sources listed with it. Status shows how well established it is.

    1. [1]

      In 2018 experimenters reported superconductivity at up to 1.7 K in twisted bilayer graphene near the 1.1° magic angle, tunable with an electric gate. confirmedas of 2026-10-10

    2. [2]

      In 2023 researchers observed the fractional quantum anomalous Hall effect, fractionally quantised Hall resistance with no applied magnetic field, in twisted bilayer MoTe2, enabling research into charge fractionalisation and anyonic statistics without external magnetic fields. confirmedas of 2026-10-10

    3. [3]

      A rhombohedral five-layer graphene/hBN moiré superlattice showed integer and fractional quantum anomalous Hall effects at zero magnetic field at several filling factors, reported in Nature in 2024. confirmedas of 2026-10-10

    4. [4]

      A Nature paper published on 15 July 2026 reported quantum anomalous Hall insulators with Chern numbers from 1 to 7 and an exotic fractional Chern insulator with C = 7/3 in a moiré system of Bernal bilayer and rhombohedral tetralayer graphene. confirmedas of 2026-10-10

    5. [5]

      A 2011 theory paper predicted that at "magic" twist angles of about one degree, the lowest moiré band of twisted bilayer graphene becomes flat and electron velocity at the Dirac point vanishes. confirmedas of 2026-10-10

    6. [6]

      The phase diagram of magic-angle graphene shows similarities to that of the cuprate high-temperature superconductors, including superconducting domes, making it the first purely carbon-based 2D superconductor. confirmedas of 2026-10-10

    7. [7]

      Isolated atomic planes of graphene and other 2D crystals can be reassembled layer by layer into designer "van der Waals heterostructures". confirmedas of 2026-10-10

    8. [8]

      Topology is the branch of mathematics describing properties that change only in steps; in physics it explains why some quantities, such as certain conductances, come in exact integer steps. confirmedas of 2026-10-10

    9. [9]

      The Royal Swedish Academy of Sciences said topological materials could find uses in new generations of electronics and superconductors and in future quantum computers. confirmedas of 2026-10-10

    10. [10]

      MIT and Harvard physicists reported in two Nature papers on 5 March 2018 that magic-angle graphene behaves like a Mott-type insulator and, when small amounts of electrons are added with a voltage, becomes superconducting without contact with other superconductors. confirmedas of 2018-03-05

    11. [11]

      Because magic-angle graphene superconducts at a relatively high temperature for its very low carrier density, its discoverers placed it among the most strongly coupled superconductors, near the BCS-BEC crossover. confirmedas of 2018-03-05

    12. [12]

      The MIT team leader suggested graphene could serve as a platform for studying unconventional superconductivity and might even yield a superconducting transistor that switches between superconducting and insulating states. confirmedas of 2018-03-05

    Revision history (2)
    1. Page created.
    2. Added the 2018 insulator-and-superconductor discovery, strong-coupling result and the superconducting-transistor idea.

    Created Oct 10, 2026. Last reviewed by an editor on Oct 10, 2026. Next scheduled review: Jan 10, 2027.

    Cite this page

    "Twisted bilayer graphene and twistronics." ContentLora, updated Oct 10, 2026. https://contentlora.com/wiki/twisted-bilayer-graphene

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