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arXiv · 0812.3983

Tunneling studies in a homogeneously disordered s-wave superconductor: NbN

S. P. Chockalingam·Madhavi Chand·Anand Kamlapure·John Jesudasan·Archana Mishra·Vikram Tripathi·Pratap Raychaudhuri
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Abstract

We report the evolution of superconducting properties as a function of disorder in homogeneously disordered epitaxial NbN thin films grown on (100) MgO substrates, studied through a combination of electrical transport, Hall Effect and tunneling measurements. The thickness of all our films are >50nm much larger than the coherence length ~5nm. The effective disorder in different films encompasses a large range, with the Ioffe-Regel parameter varying in the range kFl~1.38-8.77. Tunneling measurements on films with different disorder reveals that for films with large disorder the bulk superconducting transition temperature (Tc) is not associated with a vanishing of the superconducting energy gap, but rather a large broadening of the superconducting density of states. Our results provide strong evidence of the loss of superconductivity via phase-fluctuations in a disordered s-wave superconductor.

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S. P. Chockalingam, Madhavi Chand, Anand Kamlapure, John Jesudasan, Archana Mishra, Vikram Tripathi, Pratap Raychaudhuri. 2008-12-21. Tunneling studies in a homogeneously disordered s-wave superconductor: NbN. https://doi.org/10.1103/physrevb.79.094509

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