Suppression of the superconductivity in ultrathin amorphous Mo₇₈Ge₂₂ films observed by STM

• Published in: Физика низких температур
• Date: 2017
• Main Authors: Lotnyk, D., Onufriienko, O., Samuely, T., Shylenko, O., Komanický, V., Szabó, P., Feher, A., Samuely, P.
• Format: Article
• Language: English
• Published: Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України 2017
• Subjects: Low dimensionality and inhomogeneity effects in quantum matter
• Online Access: https://nasplib.isofts.kiev.ua/handle/123456789/174620
• Journal Title: Digital Library of Periodicals of National Academy of Sciences of Ukraine
• Cite this: Suppression of the superconductivity in ultrathin amorphous Mo₇₈Ge₂₂ films observed by STM / D. Lotnyk, O. Onufriienko, T. Samuely, O. Shylenko, V. Komanický, P. Szabó, A. Feher, P. Samuely // Физика низких температур. — 2017. — Т. 43, № 8. — С. 1146-1150. — Бібліогр.: 16 назв. — англ.

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 Mo₇₈Ge₂₂–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 to 7 K. The two-dimensional cross-correlation between topography and normalized zero-bias conductance 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.