Graphene's failed superconductor state gets caught in the act

Overview

Updated Sep 25

MIT physicists have mapped two competing states of matter in ultra-clean rhombohedral graphene: pockets where resistance drops to zero, and adjacent pockets where it stubbornly saturates at a finite value no matter how cold the sample gets. The finite-resistance state reproduces the anomalous metal, a phenomenon seen in disordered thin-film superconductors for four decades but never explained.

The platform matters because it is nearly pristine. Every previous anomalous-metal sighting involved disordered films where skeptics could blame sample imperfections. Rhombohedral graphene's gate-tunable parameters let the team expand, merge, and relocate the two phases at will, placing the strongest constraints yet on extrinsic explanations.

Why it matters

If the anomalous metal is a genuine quantum state, a 40-year-old puzzle in condensed matter physics gets its first clean test platform — and a path toward understanding dissipation in superconductors.

Questions about this story

Free account needed to ask — your question is kept and asked for you right after sign-up. Answers are public.

No questions yet — be the first to ask.

Key Indicators

61 mK

Superconducting transition temperature

Berezinskii–Kosterlitz–Thouless analysis of the true superconducting pocket yields this transition temperature.

40 years

Age of the anomalous metal puzzle

The finite-resistance state has been observed in disordered thin films since the 1980s without an accepted theoretical explanation.

Material classes now hosting multiple superconducting states

Rhombohedral graphene follows cuprates and iron-based superconductors in this regard, per MIT News analysis.

Voices

Curated perspectives — historical figures and your fellow readers.

People Involved

Long Ju

Lead researcher, MIT associate professor of physics

Active in rhombohedral graphene research at MIT

Organizations Involved

Massachusetts Institute of Technology (MIT)

Research university

Research institution behind the rhombohedral graphene experiments

MIT's condensed matter physics group produces the rhombohedral graphene devices behind this and related superconducting discoveries.

Timeline

September 2025 September 2026

3 events Latest: September 23rd, 2026 · 2 months ago

September 2026
Anomalous metal and superconducting phases reported in Nature
Latest Publication

Rhombohedral graphene on WSe2 shows zero-resistance and finite-resistance superconducting pockets; the finite-resistance state reproduces anomalous metal phenomenology.
September 23rd, 2026
June 2026
Magnetic field-boosted superconductors reported in rhombohedral graphene
Publication

Po-Wei Huang, Long Ju and MIT collaborators reported superconducting states enhanced or induced by applied magnetic fields.
June 29th, 2026
September 2025
Rhombohedral graphene research intensifies toward anomalous metal study
Research

MIT group extends rhombohedral graphene experiments to map full gate-voltage landscape at millikelvin temperatures.
September 2025

Scenarios

Anomalous metal identified as genuine quantum state in ultra-clean platform

Likely Resolves by Sep 23, 2027

Discussed by: MIT researchers and theorists cited in the Nature paper

The rhombohedral graphene platform lets experiments sweep gate voltages and in-plane fields continuously, testing predictions of competing theories — quantum phase fluctuations, dissipation from normal quasiparticles, vortex glass, or percolating superconducting islands. A definitive match to one theory would establish the anomalous metal as an intrinsic quantum state rather than a disorder artifact.

Superconducting and anomalous metal pockets shown to be one quantum phase transition

Possible Resolves by Mar 1, 2028

Discussed by: MIT group and paper's authors

The near-identical critical behavior of both phases — same abrupt transitions, same response to temperature and field — hints at a single underlying quantum phase transition. An in-plane field of a few hundred millitesla merges the pockets. Experiments pushing to lower base temperatures or higher fields could confirm a sharp quantum critical line separating the two states.

Extrinsic explanation resurfaces as device-specific effects

Unlikely Resolves by Sep 23, 2027

Discussed by: Skeptics of anomalous metal interpretations

Despite the cleanliness of rhombohedral graphene, unresolved questions about Joule heating, current inhomogeneity, or WSe2 substrate coupling could still account for the finite resistance. The paper's own BKT analysis shows the anomalous metal pocket never satisfies the superconducting criterion, leaving room for alternative readings.

Historical Context

2 moments from history that rhyme with this story — and how they unfolded.

1980s-present

Anomalous metal in thin-film superconductors (1980s onward)

Decades of experiments on quench-condensed aluminum films, granular metals, amorphous molybdenum–germanium films, and ion-gated 2D superconductors found finite resistance that refused to vanish at low temperature. Each sighting came with substantial disorder, so skeptics blamed inhomogeneous current paths, heating, or sample imperfections.

Then

The anomalous metal became a recurring puzzle: its signatures reproduced across material classes but never in a clean platform.

Now

No accepted theory emerged, leaving the field without a decisive experiment to discriminate competing explanations.

Why this matters now

Rhombohedral graphene's high carrier mobility and gate-tunable parameters let researchers relocate, expand, and merge the phases at will — testing the same models in a nearly pristine material.

2018-2025

Unconventional superconductivity in graphene (2018-2025)

Twisted bilayer graphene launched the field of moiré superconductivity in 2018, followed by a wave of graphene-based superconducting systems. Rhombohedral graphene emerged in 2025 with chiral superconductivity evidence — a discovery that broke the moiré requirement, using flat multilayer stacks instead.

Then

Rhombohedral graphene became a new platform for studying unconventional superconductivity, including magnetic-field-boosted states reported in 2026.

Now

The material's tunability positions it as a testbed for pairing mechanisms, with implications for topological quantum computing via Majorana fermions.

Why this matters now

The anomalous metal study extends this program, showing rhombohedral graphene hosts both zero-resistance and finite-resistance superconducting phases — adding a new dimension to the platform's capability.