Suppression of the superconductivity in ultrathin amorphous Mo\(_{78}\)Ge\(_{22}\) thin films observed by STM

In contact with a superconductor, a normal metal modifies its properties due to Andreev reflection. In the current work, the local density of states (LDOS) of superconductor - normal metal Mo\(_{78}\)Ge\(_{22}\) - Au bilayers are studied by means of STM applied from the Au side. Three bilayers have...

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Bibliographic Details
Published in:arXiv.org 2017-04
Main Authors: Lotnyk, D, Onufriienko, O, Samuely, T, Shylenko, O, Komanicky, V, Szabo, P, Feher, A, Samuely, P
Format: Article
Language:English
Subjects:
Bilayers
Germanium
Glass substrates
Gold
Proximity effect (electricity)
Resistance
Superconductivity
Thin films
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Summary:In contact with a superconductor, a normal metal modifies its properties due to Andreev reflection. In the current work, the local density of states (LDOS) of superconductor - normal metal Mo\(_{78}\)Ge\(_{22}\) - Au bilayers are studied by means of STM applied from the Au side. Three bilayers have been prepared on silicate glass substrate consisting of 100, 10 and 5 nm MoGe thin films covered always by 5 nm Au layer. The tunneling spectra were measured at temperatures from 0.5 K to 7 K. The two-dimensional cross-correlation between topography and normalized zero-bias conductance (ZBC) indicates a proximity effect between 100 and 10 nm MoGe thin films and Au layer where a superconducting gap slightly smaller than that of bulk MoGe is observed. The effect of the thinnest 5 nm MoGe layer on Au leads to much smaller gap moreover the LDOS reveals almost completely suppressed coherence peaks. This is attributed to a strong pair-breaking effect of spin-flip processes at the interface between MoGe films and the substrate.
ISSN:2331-8422
DOI:10.48550/arxiv.1704.06052