Phase Diagrams of Ferromagnet-Superconductor Multilayers with Misaligned Exchange Fields

TL;DR

This paper investigates how the misalignment of ferromagnetic exchange fields affects the phase diagrams and critical temperature of superconductor-ferromagnet multilayer structures, revealing transitions between different ground states.

Contribution

It introduces a new efficient method for calculating the critical temperature in ferromagnet-superconductor multilayers with misaligned exchange fields.

Findings

Transition between zero-phase and pi-phase states as a function of misalignment angle

Phase diagrams showing the dependence of Tc on magnetization orientation

Effective computational method for Tc in diffusive multilayer structures

Abstract

We study the influence of misalignment of the ferromagnetic exchange field on the equilibrium properties of hybrid structures, composed of superconducting (S) and ferromagnetic (F) parts. In particular, we study numerically the superconducting critical temperature Tc in F-S-F trilayers and in F-S-F-S-F Josephson junctions as a function of the misalignment angle theta of the ferromagnetic magnetization. We discuss the corresponding phase diagrams for these hybrid structures. For the Josephson junctions, a transition between the zero-phase and the pi-phase ground state as a function of theta takes place under certain conditions. Within the quasiclassical Green's function technique in the diffusive limit, we introduce a fast and effective method for calculating Tc in such multilayer structures.