Magnetic fields kill superconductivity. The orbital effect disrupts Cooper pairs through the Lorentz force; the Pauli paramagnetic effect breaks spin-singlet pairs by aligning spins. The Pauli limit sets an upper critical field beyond which superconductivity cannot survive for conventional spin-singlet pairing.
In hexalayer rhombohedral graphene, Xia, Su, and colleagues observe the opposite. Superconductivity appears when a magnetic field is applied and persists well beyond the Pauli limit. The field doesn't destroy the superconducting state — it creates it.
The mechanism is Fermi surface reconstruction. The hexalayer graphene hosts a nematic state — a symmetry-broken phase where the Fermi surface distorts from its equilibrium shape. The in-plane magnetic field drives the nematic reconstruction, producing a Fermi surface geometry that supports pairing. Without the field, the Fermi surface is wrong for superconductivity. With the field, it's right.
The superconductivity persisting beyond the Pauli limit is the second surprise. In conventional superconductors, this would require spin-triplet pairing. In graphene, the electronic structure allows spin-polarized pairing mediated by the nematic order — a pairing mechanism where both electrons have the same spin orientation, making the Pauli limit irrelevant because there's no spin-singlet to break.
The field creates the conditions (Fermi surface shape) and the field doesn't destroy the result (spin-polarized pairing immune to Pauli depairing). Magnetic-field-induced superconductivity in a material that sits in a single laboratory, without extreme pressure or exotic chemistry.