Transfer-matrix approach to multiband Josephson junctions

Abstract

We study the influence of multiple bands on the properties of Josephson junctions. In particular we focus on the two gap superconductor magnesium diboride. We present a formalism to describe tunneling at a point contact between two MgB2 electrodes generalizing the transfer-matrix approach to multiple bands. A simple model is presented to determine the effective hopping amplitudes between the different energy bands as a function of the misorientation angle of the electrodes. We calculate the critical current and the current-voltage characteristics for N-I-S and S-I-S contacts with different orientation for junctions with both high and low transparency. We find that interband tunneling processes become increasingly important with increasing misorientation angle. This is reflected in certain features in the differential tunneling conductance in both the tunneling limit as well as for multiple Andreev reflections.

13 pages, 8 figures

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• General Boundary Conditions for Quasiclassical Theory of Superconductivity in the Diffusive Limit: Application to Strongly Spin-polarized Systems
• The scattering problem in non-equilibrium quasiclassical theory of metals and superconductors: general boundary conditions and applications
• Break-junction technique in application to layered superconductors (Review article)
• The quasiclassical theory for interfaces with spin--orbit coupling
• Using Josephson junctions to determine the pairing state of superconductors without crystal inversion symmetry
• Spin-polarized multiple Andreev reflections in spin-split superconductors
• Impurity Scattering Rate and Coherence factor in Vortex Core of Sign-reversing s-wave Superconductors