Proximity fingerprint of s+- superconductivity

Abstract

We suggest a straightforward and unambiguous test to identify possible opposite signs of superconducting order parameter in different bands proposed for iron-based superconductors (s+- state). We consider proximity effect in a weakly coupled sandwich composed of a s+- superconductor and thin layer of s-wave superconductor. In such system the s-wave order parameter is coupled differently with different s+- gaps and it typically aligns with one of these gaps. This forces the other s+- gap to be anti-aligned with the s-wave gap. In such situation the aligned band induces a peak in the s-wave density of states (DoS), while the anti-aligned band induces a dip. Observation of such contact-induced negative feature in the s-wave DoS would provide a definite proof for s+- superconductivity.

4 pages, one figure

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• Using Gap Symmetry and Structure to Reveal the Pairing Mechanism in Fe-based Superconductors
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• Proximity and Josephson effects in microstructures based on multiband superconductors
• Anomalous proximity effects at the interface of s and s+- superconductors
• Phase diagram of Josephson junction between s and s+- superconductors in dirty limit
• Josephson current and density of states in proximity circuits with s+- superconductors
• Quantum Waveguide Theory of the Josephson effect in Multiband Superconductors
• Time-reversal symmetry breaking state in dirty three-band superconductor
• Quasiclassical circuit-theory of contiguous disordered multiband superconductors
• Josephsonic diagnostic of competing orders in quantum critical multiband superconductors