Anomalous current-voltage characteristics of SFIFS Josephson junctions with weak ferromagnetic interlayers

Tairzhan Karabassov; Anastasia V Guravova; Aleksei Yu Kuzin; Elena A Kazakova; Shiro Kawabata; Boris G Lvov; Andrey S Vasenko

doi:10.3762/bjnano.11.19

Anomalous current-voltage characteristics of SFIFS Josephson junctions with weak ferromagnetic interlayers

Beilstein J Nanotechnol. 2020 Jan 23:11:252-262. doi: 10.3762/bjnano.11.19. eCollection 2020.

Authors

Tairzhan Karabassov¹, Anastasia V Guravova¹, Aleksei Yu Kuzin^{2

3}, Elena A Kazakova⁴, Shiro Kawabata⁵, Boris G Lvov¹, Andrey S Vasenko^{1

6}

Affiliations

¹ National Research University Higher School of Economics, 101000 Moscow, Russia.
² Skolkovo Institute of Science and Technology, 121205 Moscow, Russia.
³ Department of Physics, Moscow State Pedagogical University, 119992 Moscow, Russia.
⁴ Sechenov First Moscow State Medical University, 119991 Moscow, Russia.
⁵ National Institute of Advanced Industrial Science and Technology,1-1-1 Umezono, Tsukuba, Ibaraki 305-8563, Japan.
⁶ I.E. Tamm Department of Theoretical Physics, P.N. Lebedev Physical Institute, Russian Academy of Sciences, 119991 Moscow, Russia.

Abstract

We present a quantitative study of the current-voltage characteristics (CVC) of SFIFS Josephson junctions (S = bulk superconductor, F = metallic ferromagnet, I = insulating barrier) with weak ferromagnetic interlayers in the diffusive limit. The problem is solved in the framework of the nonlinear Usadel equations. We consider the case of a strong tunnel barrier such that the left SF and the right FS bilayers are decoupled. We calculate the density of states (DOS) in SF bilayers using a self-consistent numerical method. Then we obtain the CVC of corresponding SFIFS junctions, and discuss their properties for different set of parameters including the thicknesses of ferromagnetic layers, the exchange field, and the magnetic scattering time. We observe an anomalous nonmonotonic CVC in case of weak ferromagnetic interlayers, which we attribute to DOS energy dependencies in the case of small exchange fields in the F layers.

Keywords: Josephson junctions; current–voltage characteristics; proximity effect, superconductivity; superconductor/ferromagnet hybrid nanostructures.