Magnetic-field-induced superconductivity in hexalayer rhombohedral graphene

TL;DR

This paper reports the discovery of magnetic-field-induced superconductivity in hexalayer rhombohedral graphene, revealing unconventional spin-polarized states that challenge traditional understanding of magnetic suppression of superconductivity.

Contribution

It demonstrates in-plane magnetic field-induced superconductivity in graphene and uncovers electric-field control of depairing, revealing a novel mechanism for superconductivity.

Findings

Superconductivity appears under small in-plane magnetic fields.

Superconductivity persists up to 14 T, exceeding the Pauli limit.

Superconductivity originates from nematic Fermi surface reconstruction.

Abstract

In conventional superconductors, superconductivity is generally suppressed by external magnetic fields due to spin-singlet pairing. Here, we report signatures of in-plane-magnetic-field-induced superconductivity in hexalayer rhombohedral graphene and reveal electric-field control of its depairing behavior. With the application of a small in-plane magnetic field $B_{\parallel}$, a superconducting state emerges within a narrow band along a phase boundary. Its properties evolve continuously with increasing $B_{\parallel}$: the superconducting region progressively shifts toward higher electric field as the $B_{\parallel}$ increases and the transition temperature rises with increasing $B_{\parallel}$. Remarkably, the superconducting state remains robust under $B_{\parallel}$ up to 14 T, far exceeding the conventional Pauli limit. Quantum oscillation measurements further reveal that the superconductivity emerges from nematic Fermi surface reconstruction. These results suggest a spin-polarized superconducting states with unconventional origins.