In bulk materials, superconductivity is remarkably robust with respect to non-magnetic disorder. In the two-dimensional limit, however, disorder and electron correlations both tend to destroy the quantum condensate. Here we study, both experimentally and theoretically, the effect of structural disorder on the local spectral response of crystalline superconducting monolayers of lead on silicon. In a direct scanning tunnelling microscopy measurement, we reveal how the local superconducting spectra lose their conventional character and show variations at scales significantly shorter than the coherence length. We demonstrate that the precise atomic organization determines the robustness of the superconducting order with respect to structural defects, such as single atomic steps, which may disrupt superconductivity and act as native Josephson barriers. We expect that our results will improve the understanding of microscopic processes in surface and interface superconductivity, and will open a new way of engineering atomic-scale superconducting quantum devices.
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Critical reading of our manuscript by G. Deutscher and N. Trivedi is gratefully acknowledged. This work was supported by University Pierre et Marie Curie UPMC ‘Emergence’ project, French ANR Project ‘ElectroVortex’, ANR-QuDec and Templeton Foundation (40381), ARO (W911NF-13-1-0431) and CNRS PICS funds. Partial funding by US-DOE grant DE-AC02-07CH11358 is also acknowledged. The participation of G. Ménard and R. Federicci in some of the measurements is acknowledged.
The authors declare no competing financial interests.
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Brun, C., Cren, T., Cherkez, V. et al. Remarkable effects of disorder on superconductivity of single atomic layers of lead on silicon. Nature Phys 10, 444–450 (2014). https://doi.org/10.1038/nphys2937
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