Quasiclassical circuit theory of contiguous disordered multiband superconductors

Abstract

We consider a general problem of a Josephson contact between two multiband superconductors with coexisting superconducting and magnetic phases. As a particular example, we use the quasiclassical theory of superconductivity to study the properties of a Josephson contact between two disordered s±-wave superconductors allowing for the coexistence between superconductivity and spin-density-wave orders. The intra- and interband disorder-induced scattering is treated within the self-consistent Born approximation. We calculate the spatial profile of the corresponding order parameters on both sides of the interface with a finite reflection coefficient and use our results to evaluate the local density of states at the interface as well as critical supercurrent through the junction as a function of phase or applied voltage. Our methods are particularly well suited for describing spatially inhomogeneous states of iron-based superconductors where controlled structural disorder can be created by an electron irradiation. We reveal the connection between our theory and the circuit theory of Andreev reflection and extend it to superconducting junctions of arbitrary nature. Lastly, we outline directions for further developments in the context of proximity circuits of correlated electron systems.

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