Thermodynamic properties of ferromagnetic/superconductor/ferromagnetic nanostructures

TL;DR

This paper presents a theoretical analysis of the thermodynamic properties of ferromagnetic/superconductor/ferromagnetic nanostructures, highlighting how their superconducting behavior depends on layer orientation and interface transparency, with implications for spin-valve experiments.

Contribution

It introduces a theoretical framework for understanding thermodynamic properties of F/S/F nanostructures, including dependence on magnetic orientation and interface transparency.

Findings

Superconducting critical temperature varies with F-layer thickness and interface transparency.

The mutual orientation of ferromagnetic layers significantly affects superconducting characteristics.

Spontaneous transition from parallel to anti-parallel magnetic alignment is predicted.

Abstract

The theoretical description of the thermodynamic properties of ferromagnetic/superconductor/ferromagnetic (F/S/F) systems of nanoscopic scale is proposed. Their superconducting characteristics strongly depend on the mutual orientation of the ferromagnetic layers. In addition, depending on the transparency of S/F interfaces, the superconducting critical temperature can exhibit four different types of dependences on the thickness of the F-layer. The obtained results permit to give some practical recommendations for the spin-valve effect experimental observation. In this spin-valve sandwich, we also expect a spontaneous transition from parallel to anti-parallel ferromagnetic moment orientation, due to the gain in the superconducting condensation energy.