Resonance Properties of the Josephson Junctions with Ferromagnets
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sonance Properties of the Josephson Junctions with Ferromagnets Yu. M. Shukrinova, b, * and I. R. Rahmonova, c, ** a
Joint Institute for Nuclear Research, Dubna, 141980 Russia b Dubna State University, Dubna, 141980 Russia c Umarov Institute of Physics and Technology, Academy of Sciences of the Republic of Tajikistan, Dushanbe, 734063 Tajikistan *e-mail: [email protected] **e-mail: [email protected] Received December 20, 2019; revised January 16, 2020; accepted January 29, 2020
Abstract—In the paper, the results of the study of ferromagnetic resonance in a ϕ0 junction, in which the phase difference couples directly to the magnetic moment of the barrier, are presented. We have calculated current–voltage characteristics, average superconducting current dependences on the bias current and voltage, and dependences of the maximum amplitude of the magnetization components on the applied voltage at different parameters of spin–orbit coupling. We show the emergence of a constant component of a superconducting current as the effect of coupling between the magnetization and the spin–orbit interaction, and we clarify the role of the coupling in the transformations of current-voltage characteristics occurring in the resonance region. The results presented can be used to develop new resonance techniques for determining the spin–orbit coupling parameter in noncentrosymmetric materials. DOI: 10.1134/S1063779620040668
INTRODUCTION Recently, the models describing the interaction of the superconducting current and the magnetic moment in structures of the “superconductor–ferromagnet–superconductor” type, which are important for a number of problems of superconducting spintronics, have been attracting great attention [1–4]. As mentioned in [1], the spintronic research helped to understand fundamental spin-dependent phenomena and to develop applications for new computer technologies. In particular, controlling the magnetic state by superconductivity provides new opportunities for the development of ultrafast cryogenic memory. The relationship between the Josephson current and magnetization may be due to various causes. Thus, the Rashba-type spin–orbit coupling in a ferromagnet with the broken symmetry of inversion leads to a phase shift in the Josephson junction proportional to the magnetic moment in the barrier. Consequently, the so-called ϕ0 junction appears, in which the phase difference couples directly to the magnetic moment of the barrier [5, 6], which determines the unique possibilities to control the barrier magnetic properties by the superconducting current and, in turn, the possibility to influence the Josephson current by the barrier magnetic moment [1–11]. In [3, 6], the authors reported a possibility of reorientation of easy magnetization axis in the presence of spin–orbit coupling. Assuming that the easy axis is initially directed along the z axis, they showed that when the superconducting
current was applied, magnetization acquired a certain stable orientation directed between the z and y axes depending on th
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