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Subharmonic gap structure in d-wave superconductors

A. Poenicke·J. C. Cuevas·M. Fogelstrom
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Abstract

We present a self-consistent theory of current-voltage characteristics of d-wave/d-wave contacts at arbitrary transparency. In particular, we address the open problem of the observation of subharmonic gap structure (SGS) in cuprate junctions. Our analysis shows that: (i) the SGS is possible in d-wave superconductors, (ii) the existence of bound states within the gap results in an even-odd effect in the SGS, (iii) elastic scattering mechanisms, like impurities or surface roughness, may suppress the SGS, and (iv) in the presence of a magnetic field the Doppler shift of the Andreev bound states leads to a very peculiar splitting of the SGS, which is an unambiguous fingerprint of d-wave superconductivity.

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A. Poenicke, J. C. Cuevas, M. Fogelstrom. 2002-03-25. Subharmonic gap structure in d-wave superconductors. https://doi.org/10.1103/physrevb.65.220510

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