MIT uncovers a new family of superconductors in rhombohedral graphene that defy magnetic fields

In a series of landmark studies published between 2025 and 2026, MIT researchers led by Long Ju's group have uncovered a rich landscape of unconventional superconducting states in rhombohedral-stacked multilayer graphene — a crystalline, non-twisted form of graphene found naturally in some graphite. The discoveries challenge decades-old assumptions about how superconductors behave in magnetic fields and could open new pathways for topological quantum computing.

Multiple superconducting states across layer numbers

The MIT team found that the number of distinct superconducting phases scales with the number of graphene layers, each revealing new physics:

• Tetralayer graphene hosts two new superconducting states, each exhibiting both chirality and intrinsic magnetism — a combination never before observed in a superconductor. The MIT Research Laboratory of Electronics reports transition temperatures up to ~300 mK .
• Pentalayer graphene contains three different types of field-enhanced and field-induced superconductivities, all robust against in-plane magnetic fields up to 8.5 T .
• Hexalayer graphene reveals a superconducting phase that simultaneously breaks rotational, translational, and time-reversal symmetries, emerging from a quarter-metallic state with stripe charge order .
• Heptalayer graphene also shows multiple superconducting phases, reinforcing that this phenomenon scales with layer number .

A June 2026 study in Nature summarized that a single graphene microstructure can hold a whole family of unconventional superconducting states .

Defying magnetic fields — and flipping the script

Conventional (s-wave) superconductivity is destroyed by magnetic fields through orbital depairing (out-of-plane) and Pauli paramagnetic depairing (in-plane). The MIT discoveries repeatedly invert this expectation:

• Out-of-plane field stabilization: In hexalayer graphene, a superconducting phase is not destroyed but instead stabilized by an out-of-plane magnetic field. This state coexists and competes with quantum Hall states — two phenomena traditionally regarded as mutually exclusive .
• In-plane field resilience: Multiple superconducting states in tetra-, penta-, and heptalayer graphene persist well beyond the conventional Pauli limit, with critical in-plane fields exceeding 8.5 T, which exceeds the limit by tens of times .
• Field-induced superconductivity: In some regimes, applying an in-plane magnetic field drives an insulator-superconductor transition — the opposite of standard behavior .
• Striped superconductor: The hexalayer state coexists with stripe charge order and spontaneously breaks time-reversal symmetry, forming one-dimensional-like superconducting channels while the orthogonal direction remains resistive .

Proposed mechanism: spin-triplet pairing

The MIT team proposes that these unusual properties arise from spin-triplet pairing rather than conventional spin-singlet pairing . Key theoretical elements:

• The normal state in these systems is isospin-polarized (spin and/or valley polarized), breaking time-reversal symmetry before superconductivity even sets in .
• Superconductivity emerges from a quarter-metal parent state — characterized by a single spin, single valley, single band, and single Fermi pocket .
• The observed robustness against magnetic fields is a hallmark of spin-triplet or chiral superconducting order parameters, where electron pairs are aligned rather than opposite in spin .
• In the hexalayer system, the proposed state is a "striped" superconductor with a complex, multi-component order parameter .

Broader implications

These findings are significant for the study of unconventional superconductivity:

• A tunable platform: Rhombohedral multilayer graphene provides a clean, moiré-free, gate-tunable platform for systematically studying unconventional superconductivity across different layer numbers .
• Chiral superconductivity: The coexistence of superconductivity and intrinsic magnetism in a single material confirms the existence of chiral superconductors — a long-theorized but rarely observed state .
• Spin-triplet pairing: The magnetic-field resilience provides some of the strongest evidence to date for spin-triplet superconductivity in a solid-state system .
• Topological superconductivity: Several theoretical works predict that these states may host Majorana fermions and spontaneous vortex-antivortex lattices, relevant for topological quantum computing .
• Beyond moiré systems: These discoveries show that unconventional superconductivity does not require magic-angle moiré superlattices — it can arise from the intrinsic electronic structure of rhombohedral graphene itself, greatly expanding the search space for new superconductors .

The emerging picture is that rhombohedral stacked graphene is not just one more superconductor, but a versatile laboratory for exploring the most exotic forms of superconductivity theorized over the past four decades — now sitting inside a material found in pencil lead.