Structure of the Fulde-Ferrell-Larkin-Ovchinnikov state in two-dimensional superconductors

TL;DR

This paper investigates the spatial structure of the Fulde-Ferrell-Larkin-Ovchinnikov state in two-dimensional superconductors, revealing that two-dimensional lattice structures are energetically favored over traditional one-dimensional solutions at low temperatures and high magnetic fields.

Contribution

It demonstrates that 2D lattice structures like triangular, square, and hexagonal are more stable than 1D solutions in certain regimes, depending on pairing symmetry and temperature.

Findings

2D structures have lower free energy than 1D solutions.

Triangular, square, and hexagonal states are favored depending on temperature.

Square states are favored at low temperatures for d-wave pairing.

Abstract

Nonuniform superconducting state due to strong spin magnetism is studied in two-dimensional type-II superconductors near the second order phase transition line between the normal and the superconducting states. The optimum spatial structure of the orderparameter is examined in systems with cylindrical symmetric Fermi surfaces. It is found that states with two-dimensional structures have lower free energies than the traditional one-dimensional solutions, at low temperatures and high magnetic fields. For s-wave pairing, triangular, square, hexagonal states are favored depending on the temperature, while square states are favored at low temperatures for d-wave pairing. In these states, orderparameters have two-dimensional structures such as square and triangular lattices.