Exceedingly large in-plane critical field of finite-momentum pairing state in bulk superlattices

TL;DR

This paper reports the discovery of a bulk superlattice exhibiting an orbital effect-induced finite-momentum pairing state with an in-plane critical field exceeding eight times the Pauli limit, revealing new possibilities for unconventional superconductivity.

Contribution

It demonstrates the existence of a finite-momentum pairing state in bulk materials under large magnetic fields, driven by orbital effects, distinct from traditional FFLO states.

Findings

In-plane critical field exceeds eight times the Pauli limit.

Pronounced anisotropic transport behavior under high magnetic fields.

Finite-momentum pairing state remains robust against moderate disorder.

Abstract

Magnetic flux profoundly influences the phase factor of charge particles, leading to exotic quantum phenomena. A recent example is that the orbital effect of magnetic field could induce finite-momentum pairing state in nanoflakes, which offers a new pathway to realize the spatially modulated superconductivity distinct from the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state induced by Zeeman effect. However, whether such intriguing state can exist in the bulk materials under extremely large magnetic field remains elusive. Here we report the orbital effect induced finite-momentum pairing state with exceedingly large in-plane critical field in a bulk superconducting superlattice. Remarkably, the in-plane critical field shows a pronounced upturn behavior, exceeding eight times the Pauli limit which is comparable to monolayer Ising superconductor. Under high in-plane magnetic fields, significant anisotropic transport behavior between the interlayer and intralayer directions is detected, highlighting the critical role of suppressed interlayer coherence in the orbital effect induced finite-momentum pairing state. Crucially, this finite-momentum pairing state remains robust against moderate disorder. Our findings suggest that van der Waals superlattices, with strong Ising spin-orbit coupling and tunable interlayer coherence, offer new avenues for constructing and modulating unconventional superconducting states.