Maxim Avdeev

The influence of an external magnetic field on the triplet proximity effect in ferromagnet/superconductor trilayers

The properties of the ferromagnet/superconductor (FS) system are theoretically studied in an external magnetic field. We consider the boundary value problem for the Usadel-like equations in the case of the so-called ?dirty? limit. Based on a fit of theoretical and known experimental data for the real symmetrical CuNi/Nb/CuNi trilayer, we expand upon numerical predictions on the asymmetrical F1SF2 and F1F2S systems. It is shown that the asymmetry essentially influences the critical properties of both the trilayers. The appearance of peculiar solitary re-entrant superconductivity caused by an external magnetic field is predicted for the F1F2S system.

INHOMOGENEOUS CURRENT DISTRIBUTION IN A BIMETAL FERROMAGNET/SUPERCONDUCTOR FILM IN A LONGITUDINAL MAGNETIC FIELD

The proximity effect of the ferromagnetic metal/superconductor (FM/S) bilayers in а external longitudinal magnetic field is considered in the dirty limit. The critical temperature and the superconducting current distribution versus applied magnetic field’s magnitude, film’s thicknesses and a transparency of the contact is calculated, with taking into account аn umklapp processes possibility on the interface of the FM/S contact. It is shown that superconducting current is strictly inhomogeneous and asymmetrical. It is shown also that the current inhomogeneity depends heavily from the FM/S interface transparency.

How experimentally to detect a solitary superconductivity in dirty ferromagnet-superconductor trilayers?

Abstract We theoretically study the proximity effect in the thin-film layered ferromagnet (F) – superconductor (S) heterostructures in F 1 F 2 S design. We consider the boundary value problem for the Usadel-like equations in the case of so-called “dirty” limit. The “latent” superconducting pairing interaction in F layers taken into account. The focus is on the recipe of experimental preparation the state with so-called solitary superconductivity. We also propose and discuss the model of the superconducting spin valve based on F 1 F 2 S trilayers in solitary superconductivity regime.

Proximity Effect for Asymmetrical Three-Layered FS Structures in External Magnetic Field

We study asymmetrical three-layers F1F2S and F1SF2 structures in an external parallelmag-netic field. Assuming that all F and S layers are dirty, we solve the boundary value problem for theUsadel function. We calculate the critical temperature of in the F1F2S and F1SF2 systems as functionof the F layers thicknesses and external magnetic field.

Critical temperature of a ferromagnet/superconductor structures in a parallel magnetic field

Two- and three-layered structures consisting of ferromagnetic metal (F) film and superconductor (S) film are considered in the magnetic field H applied parallel to the plane of the F/S interface. Magnetic-penetration depth is presumed much greater than thicknesses of layers. Assuming that both S and F layers are dirty the boundary problem for the Usadel function is solved taking account of so called Umklapp processes for momenta of superconducting pairs on the F/S interface. It is shown that the field H can significantly alter a functional form of the dependence of critical temperature Tc versus thickness of the F layer df. Keeping in mind the possible applications like the superonducting spin-valve the behavior of Tc(df) for the F/S/F trilayer in the magnetic field is investigated.