On the origin of in-gap states in homogeneously disordered ultrathin films. MoC case

Abstract

Many disordered superconducting films exhibit smeared tunneling spectra with evident in-gap states. We demonstrated that the tunneling density of states in ultrathin MoC films is gapless and can be described by the Dynes version of the BCS density of states with a strong broadening parameter Gamma accounting for the suppression of coherence peaks and increased in-gap states. The thinner the film, the lower the Tc and the superconducting energy gap Delta and the larger the Gamma. MoC films of 3 nm thickness deposited simultaneously on silicon and sapphire substrates reveal very similar scalar disorder, evidenced by the equal sheet resistance, but exhibit different superconducting characteristics of Tc, Delta and Gamma, suggesting that pair breaking responsible for the dissipation channel and the suppression of superconductivity originates on the film-substrate interface. It indicates that sapphire is a stronger pair breaker. Interface pair breaking can be operative in other cases as well.

arXiv comment9 pages, 5 figures, published in Applied Surface Science

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Cited by in corpus (4)

• Zeeman driven superconductor insulator transition in strongly disordered MoC film. STM and transport studies in transverse magnetic field
• Suppressed superconductivity in ultrathin Mo2N films due to pair-breaking at the interface
• Direct observation of intrinsic surface magnetic disorder in amorphous superconducting films
• Scanning tunneling spectroscopy of superconducting nitridized aluminum thin films