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arXiv · 1210.2546

Realization of the $π$-state in junctions formed by multi-band superconductors with a spin-density-wave

Andreas Moor·Anatoly F. Volkov·Konstantin B. Efetov
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Abstract

Using a simple model of multi-band superconductors, which can be applied in particular to Fe\nobreakdash-based pnictides, we calculate the Josephson current $I_{\text{J}}$ in a tunnel junction composed by such superconductors. We employ the tunneling Hamiltonian method and quasiclassical Green's functions. We study both the case of coexistence of the superconducting ($Δ$) and magnetic (SDW---spin density wave) order parameters and the case when only the superconducting order parameter exists. We show that the current $I_{\text{J}}$ depends on the mutual orientation of magnetization of the SDW in the case of non-ideal nesting when the coexistence of superconducting and magnetic order parameters is possible as it takes place in Fe\nobreakdash-based pnictides. It is found that the realization of the $π$\nobreakdash-junction is possible in both cases. We compare our results for multi-band superconductors without the SDW with those obtained earlier and find that they coincide if the tunneling matrix elements are real. If these elements are complex, a new term appears in the formula for the Josephson critical current.

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Andreas Moor, Anatoly F. Volkov, Konstantin B. Efetov. 2013-03-18. Realization of the $π$-state in junctions formed by multi-band superconductors with a spin-density-wave. https://doi.org/10.1103/physrevb.87.100504

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