Superconducting Transition Temperature in Heterogeneous Ferromagnet-Superconductor Systems

TL;DR

This paper investigates how ferromagnetic layers and arrays affect the superconducting transition temperature, predicting significant changes with small external magnetic fields in heterostructures.

Contribution

It provides new insights into the influence of ferromagnetic structures on superconducting transition temperatures and extends the analysis to multilayer systems.

Findings

Transition temperature shifts depend on the ferromagnetic configuration.

Small external magnetic fields can significantly alter $T_c$.

Opposite effects observed in bi-layer and dot array configurations.

Abstract

We study the shift of the the superconducting transition temperature $T_c$ in ferromagnetic-superconducting bi-layers and in a superconducting film supplied a square array of ferromagnetic dots. We find that the transition temperature in these two cases change presumably in opposite direction and that its change is not too small. We extend these results to multilayer structures. We predict that rather small external magnetic field $\sim 10$ Oe can change the transition temperature of the bilayer by 10% .