Proximity effect in superconductor/conical magnet/ferromagnet heterostructures

• Published in: New journal of physics Vol. 16; no. 5; pp. 55005 - 16
• Main Authors: Fritsch, Daniel, Annett, James F
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 06.05.2014
• Subjects: 74.45.+c; Bogoliubov-de Gennes equations; Cooper pairs; Density; Electrons; ferromagnet-superconductor interface; Ferromagnetism; Heterostructures; Mathematical analysis; Mathematical models; odd-frequency pairing; Physics; Proximity; proximity effect; Proximity effect (electricity); spin-triplet Cooper pairs; Superconductors; Thickness
• ISSN: 1367-2630; 1367-2630
• DOI: 10.1088/1367-2630/16/5/055005

At the interface between a superconductor and a ferromagnetic metal spin-singlet Cooper pairs can penetrate into the ferromagnetic part of the heterostructure with an oscillating and decaying spin-singlet Cooper pair density. However, if the interface allows for a spin-mixing effect, equal-spin spin-triplet Cooper pairs can be generated that can penetrate much further into the ferromagnetic part of the heterostructure, known as the long-range proximity effect. Here, we present results of spin-mixing based on self-consistent solutions of the microscopic Bogoliubov-de Gennes equations in the clean limit incorporating a tight-binding model. In particular, we include a conical magnet into our model heterostructure to generate the spin-triplet Cooper pairs and analyse the influence of conical and ferromagnetic layer thickness on the unequal-spin and equal-spin spin-triplet pairing correlations. It will be shown that, in agreement with experimental observations, a minimum thickness of the conical magnet is necessary to generate a sufficient amount of equal-spin spin-triplet Cooper pairs allowing for the long-range proximity effect.