Nanoscale ferromagnet-superconductor-ferromagnet switches controlled by magnetization orientation

TL;DR

This paper investigates how changing the magnetization orientation in ferromagnet-superconductor-ferromagnet nanostructures can control superconductivity, enabling on/off switching or state changes in the superconductor.

Contribution

It demonstrates that magnetization reversal in F layers can drastically alter the superconductor's state, revealing a controllable nanoscale switch mechanism.

Findings

Antiparallel magnetization favors superconductivity.

Reversing magnetization can turn superconductivity on or off.

Switching between different superconducting states is possible.

Abstract

We study clean ferromagnet-superconductor-ferromagnet (FSF) nanostructures in which the magnetization of the F layers can be parallel (P) or antiparallel (AP). We consider the case where the thickness of the S layer is of order of the coherence length, with thinner F layers. We find that reversing the direction of the magnetization in one of the F layers leads in general to drastic changes in the superconductor's state. Under a wide variety of conditions, the AP geometry favors superconductivity. Magnetization reversal in one of the F layers can lead to the superconductivity turning on and off, or to switching between different states. Our results are obtained via self consistent solution of the Bogoliubov-de Gennes equations and evaluation of the condensation energies of the system.