Extraordinary magnetic field behavior of SIFS Josephson junctions with an inhomogeneous transparency of the FS interface
M. Yu. Kupriyanov*, N. G. Pugach*, M. M. Khapaev*, A. V. Vedyayev*, E. B. Goldobin+, D. Koelle+, R. Kleiner+
*M.V. Lomonosov Moscow State University, 119992 Moscow, Russia
+Physikalisches Institut-Experimentalphysik II and Center for Collective Quantum Phenomena, Universität Tübingen, Germany
PACS: 74.50.+r, 74.80.Dm, 75.30.Et
Abstract
Within the framework of the Usadel equations the Josephson effect
in a superconductor-insulator-ferromagnet-superconductor (SIFS) structure
with spatially heterogeneous transparency of the SF interface has been
studied. It is shown that at a certain thickness of the F-layer a step-like
variation of the transparency leads to the formation of a region of size
(coherence length in a ferromagnet) where the Josephson
supercurrents of different signs may flow. This may lead to a dependence of
the junction critical current on the external magnetic field qualitatively
different from the Fraunhofer pattern typically observed in usual Josephson
junctions.