Josephson current in superconductor/ferromagnet/superconductor junctions |
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| Affiliation: | 1. Key Laboratory for Precision and Nontraditional Machining Technology of Ministry of Education, School of Mechanical Engineering, Dalian University of Technology, Dalian 116024, People''s Republic of China;2. State Key Laboratory of Structural Analysis for Industrial Equipment, Department of Engineering Mechanics, Dalian University of Technology, Dalian 116024, People''s Republic of China;1. Faculty of Chemistry, K. N. Toosi University of Technology, Tehran, Iran;2. Faculty of Chemistry, University of Tehran, Tehran, Iran;1. Department of Chemical and Biomolecular Engineering, University of Delaware, 150 Academy Street, Newark, DE 19716, USA;2. Dow, 230 Abner Jackson Parkway, Lake Jackson, TX 77566, USA |
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| Abstract: | By using the Bogoliubov–de Gennes equation and the Nambu spinor Greens function approach, we have theoretically studied the dc Josephson current and the coupling phase state of superconductor/ferromagnet/superconductor (SC/FM/SC) junctions, where the FM is of weak ferromagnetism. From the behavior of the temperature-dependent dc Josephson current (Ic), we confirm that such SC/FM/SC junction may change from 0-phase to π-phase state with increasing the temperature (T), for particular parameters of the thickness and the strength of ferromagnetism of the FM interlayer. We attribute such changement to an extra phase difference between the two SCs. The results are qualitatively consistent with an experiment [Phys. Rev. Lett. 86 (2001) 2427], which shows a sharp cusp structure on the Ic−T curves of Nb/Cu0.48Ni0.52/Nb junction for specific thickness of the Cu0.48Ni0.52, indicating the junction changes from 0-phase state at high temperatures to π-phase state at low temperatures. |
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