Место издания:Multiprint ( ООО ”ПКЦ АЛЬТЕКС” ) Moscow
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Аннотация:We study theoretically the properties of SIFS type Josephson junctions com-
posed of two superconducting (S) electrodes separated by an insulating layer (I)
and a ferromagnetic (F) region consisting of periodic magnetic domains structure
with antiparallel magnetization directions in neighboring domains. Two domain
alignments have been considered. In the irst geometry it is supposed that the
domain structure is formed in a single ferromagnetic ilm. It is a periodical struc-
ture in the direction perpendicular to the current lowing through the junction.
In the second geometry it is considered that the Josephson coupling occurs in
SFNFN...FNIS structures, in which in weak link there is a FNFN...FN multilayer
with FN interfaces located perpendicular to the direction of supercurrent low.
For the irst geometry the two-dimensional problem in the weak link area is
solved analytically in the framework of the linearized quasiclassical Usadel equa-
tions. Based on this solution, the spatial distributions of the critical current den-
sity, Jc, in the domains and critical current, Ic of SIFS structures are calculated as
a function of domain wall parameters, as well as the thickness, dF and the width,
W, of the domains. We demonstrate that Ic(dF,W) dependencies exhibit damped
oscillations with the ratio of the decay length, xi1, and oscillation period, xi2, be-
ing a function of the parameters of the domains, and this ratio may take any value
from zero to unity. Thus, we propose a new physical mechanism that may explain
the essential diference between xi1 and xi2 observed experimentally in various
types of SFS Josephson junctions.
In the second geometry we study the proximity efect in SFNFN...FN elec-
trode in the frame of Usadel equations both analytically (in the linear approxi-
mation) and numerically. We have shown that depending on the layers thickness
andmagnitudeofsuppressionparametersgammaandgammaBsuperconducting
correlations can monotonically decay in FNFN..FN multilayer or exhibit damped
oscillations and calculate the decay length, xi1, and oscillation period, xi2, as a
function of layers thickness and suppression parameters at FN boundaries.
This work was supported by RFBR grants l4-02-90018-bel a, 14-02-31002-mol
a, 15-32-20362-mol a ved, Ministry of Education and Science of the Russian Fed-
eration in the framework of Grant No. 14Y26.31.0007 and the Program for the
Promotion of Competitiveness of the Kazan Federal University among the World-
Leading Scientiic Educational Centers, Russian President grant MK-1841.2014.2,
Dynasty Foundation, Scholarship of the President of the Russian Federation and
Dutch FOM.
