Field-induced reentrant superconductivity in thin films of nodal superconductor

TL;DR

This paper investigates the stability of a novel FFLO-like superconducting state in thin nodal superconductor films under magnetic fields, revealing a reentrant superconducting phase due to the interplay of two distinct FFLO states.

Contribution

It introduces the concept of a field-induced reentrant superconducting phase in thin films of nodal superconductors, highlighting the stability of a novel modulated SC state against magnetic fields.

Findings

Presence of two FFLO states at different field regimes.

Reentrant superconductivity bounded by the normal phase.

Conventional SC state appears as a reentrant phase at lower fields.

Abstract

Previous works on nodal d-wave superconductors have shown that a Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) like modulated superconducting (SC) state can be realized with no magnetic field when quasiparticles acquire an additional linear term in the wavevector in their dispersion. In the present work, stability of such a novel modulated SC state in an artificial film against an applied magnetic field is studied. As a reflection of the presence of the two different FFLO states, one close to zero field and the other at the high field end, in a single field v.s. temperature phase diagram of thin films, the conventional uniform SC state generally tends to appear as a reentrant ordered phase bounded by the normal phase in {\it lower} fields.