Magnetic Properties of the Intermediate State in Small Type-I Superconductors

TL;DR

This paper uses simulations solving Ginzburg-Landau equations to study the intermediate state in small type-I superconductors, revealing magnetic hysteresis, geometric patterns, and the effects of initial conditions on flux structures.

Contribution

It introduces a simulation approach incorporating demagnetizing fields to analyze magnetic patterns and hysteresis in small type-I superconducting films.

Findings

Saw-tooth magnetization behavior during field increase.

Geometric patterns influenced by surface barriers.

Pattern diversity depending on initial conditions.

Abstract

We present simulations of the intermediate state of type-I superconducting films solving the time dependent Ginzburg-Landau equations, which include the demagnetizing fields via the Biot-Savart law. For small square samples we find that, when slowly increasing the applied magnetic field $H_a$, there is a saw-tooth behavior of the magnetization and very geometric patterns, due to the influence of surface barriers; while when slowly decreasing $H_a$, there is a positive magnetization and symmetry-breaking structures. When random initial conditions are considered, we obtain droplet and laberynthine striped patterns, depending on $H_a$.