Current-carrying states in superconductor/insulator and superconductor/semiconductor superlattices in the mesoscopic regime |
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Institution: | 1. Department of Physics, Kharkov State University, 310077, Kharkov, Ukraine;2. Institute for Single Crystals, 310164, Kharkov, Ukraine;1. State Key Laboratory for Mesoscopic Physics and Department of Physics, Peking University, Beijing 100871, China;2. Department of Physics, Beijing University of Aeronautics and Astronautics, Beijing 100083, China |
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Abstract: | We discuss some of the basic theoretical aspects of current-carrying states in superconducting superlattices with tunnel barriers in the mesoscopic regime, when p0 − 1 ⪡ a ⪡ ξ0(a is the superconducting layer thickness, p0is the Fermi momentum, ξ0is the BCS coherence length and ℏ = 1). We establish the necessary conditions for the observation of the classical Josephson effect (with sinusoidal current–phase dependence) and derive self-consistent analytical expressions for the critical Josephson current. These expressions are proportional to the small factor a / ξ0and have unusual temperature dependence as compared with the single-junction case. For certain parameter values, the superconducting gap exhibits an exponential decrease due to pair-breaking effect of the supercurrent. The supercurrent can completely destroy the superconductivity of the system above a certain characteristic temperature T * . In this paper, we also study the effect of intrabarrier exchange interactions. We show that this effect is strongly enhanced compared with the single-junction case and can manifest itself in an exponential decrease of the critical temperature. |
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