Fulde-Ferrell-Larkin-Ovchinnikov pairing induced by a Weyl nodal line in an Ising superconductor with a high critical field

Abstract

Superconductivity and electron topology are two quantum phenomena that have attracted much interest, but no causal relationship between them has been reported because superconductivity is a many-body effect due to electron-electron interaction, while electron topology is a single-particle manifestation of electron states. Here, we demonstrate that electron topology can induce Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) pairing in Ising Bardeen-Cooper-Schrieffer (IBCS) superconductors. Specifically, we predict that the nonmagnetic metals of the MA2Z4 family, including α1−TaSi2P4, α1−TaSi2N4, α2−TaGe2P4, α1−NbSi2P4, and α2−NbGe2P4 monolayers, are all IBCS superconductors with a transition temperature ranging from a few to tens of degrees Kelvin. The intrinsic IBCS pairing alone will enhance the in-plane critical field Bc to ∼20–60 times the Pauli limit Bp, and the extrinsic FFLO pairing evoked by topological Weyl nodal lines under a magnetic field can further double the Bc/Bp ratio. Our findings not only enrich the fundamental relationship between superconductivity and electron topology, but they also yield an effective approach to enhance the robustness of superconductivity.

Source-reported materials — not catalogue approval

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