Superconductivity in Graphene-Based Materials

Superconductivity in graphene-based systems arises from a delicate interplay of reduced dimensionality, enhanced electron–electron interactions and the engineering of electronic band structures. Pristine monolayer graphene exhibits negligible intrinsic superconductivity, but when modified by doping, intercalation or moiré patterning, it can host robust Cooper pairing. Intercalated structures with alkali or alkaline-earth metals introduce charge carriers and mediate electron–phonon coupling, producing superconducting critical temperatures in the range 4–8 K. In parallel, moiré superlattices in twisted bilayer and rhombohedral multilayer graphene create flat electronic bands that amplify correlation effects and give rise to unconventional superconductivity with chiral or spin-polarised order. The tunability of these platforms via electrostatic gating, twist angle adjustment and chemical confinement offers a versatile toolbox for probing pairing mechanisms. The global significance spans quantum technologies, where graphene’s exceptional mobility and coherence properties promise high-performance superconducting circuits, sensors and scalable quantum-information devices.

Research from Nature Portfolio

Recent studies have shown unconventional pairing mediated by inter-valley coherent fluctuations in rhombohedral trilayer graphene. Analysis of the symmetry-broken normal state indicates that strong isospin fluctuations can stabilise chiral superconductivity, with spin-structure determined by inter-valley Hund’s coupling. In bilayer graphene intercalated with calcium, first-principles anisotropic Eliashberg calculations demonstrate phonon-mediated superconductivity with a critical temperature of 6.8–8.1 K, highlighting the pivotal role of low-energy vibrational modes in pairing. Foundational experiments on calcium-doped graphene laminates reveal bulk superconductivity at 4–6 K, controlled by dopant confinement and carrier concentration, thereby providing a practical route towards free-standing superconducting monolayers.

Research from all publishers

Theoretical modelling using extended Hubbard Hamiltonians in mono- and bilayer graphene shows that finite doping can induce superconductivity via competition between local interaction channels. Renormalisation-group analysis predicts spin-singlet and spin-triplet phases depending on the dominant repulsive interaction, and identifies selection rules linking normal-state band dispersion to pairing symmetry. In parallel, tight-binding studies of chiral d-wave pairing on the honeycomb lattice demonstrate that time-reversal-odd loop currents produce a topological mass gap at the Dirac points, leading to intrinsic anomalous Hall responses in superconducting graphene and hinting at observable Kerr rotation without external magnetic fields.

Superconductivity in Graphene-Based Materials publication trend

The graph below shows the total number of articles in superconductivity in graphene-based materials across all publications each year (not limited to Nature Index journals).

Technical terms

Flat band: energy band with minimal dispersion, yielding high density of states and enhanced correlation effects.

Moiré superlattice: long-period interference pattern formed by stacking two lattices with a small twist or mismatch.

Electron–phonon coupling: interaction between electrons and lattice vibrations that can mediate Cooper pairing.

Inter-valley coherent order: ordered state in which electronic states in distinct momentum valleys form a coherent superposition.

Chiral superconductivity: superconducting state characterised by a defined handedness in the pairing symmetry, often breaking time-reversal symmetry.

Isospin: pseudospin degree of freedom associated with layer or valley indices in graphene systems.

References

1. Inter-valley coherent order and isospin fluctuation mediated superconductivity in rhombohedral trilayer graphene. Nature Communications (2022).
2. Electron-phonon interaction and pairing mechanism in superconducting Ca-intercalated bilayer graphene. Scientific Reports (2016).
3. Superconductivity in Ca-doped graphene laminates. Scientific Reports (2016).
4. Extended Hubbard model in undoped and doped monolayer and bilayer graphene: Selection rules and organizing principle among competing orders. Physical Review B (2021).
5. Loop Currents and Anomalous Hall Effect from Time-Reversal Symmetry-Breaking Superconductivity on the Honeycomb Lattice. Physical Review X (2019).