# Exotic pairing state in quasicrystalline superconductors under magnetic field

## TL;DR

This paper theoretically investigates how magnetic fields influence quasicrystalline superconductors, revealing an exotic state with a sign-changing order parameter that maintains coherence despite the lack of periodicity.

## Contribution

It introduces a novel superconducting state in quasicrystals under magnetic fields, highlighting the persistence of coherence with a sign-changing order parameter in quasiperiodic structures.

## Key findings

- Discovery of a sign-changing superconducting state in quasicrystals under high magnetic fields
- Comparison with Fulde-Ferrell-Larkin-Ovchinnikov state clarifies similarities and differences
- Superconductivity persists with a coherent, spatially modulated order parameter despite quasiperiodicity

## Abstract

We theoretically study the effect of a magnetic field on quasicrystalline superconductors, by modelling them as the attractive Hubbard model on the Penrose-tiling structure. We find that at low temperatures and under a high magnetic field there appears an exotic superconducting state with the order parameter changing its sign in real space. We discuss the state in comparison with the Fulde-Ferrell-Larkin-Ovchinnikov state proposed many years ago for periodic systems, clarifying commonalities and differences. It is remarkable that, even in the absence of periodicity, the electronic system finds a way to keep a coherent superconducting state with a spatially sign-changing order parameter compatible with the underlying quasiperiodic structure.