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

Abstract

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.

6 pages, 4 figures

References in corpus (3)

• Fermionic scenario for the destruction of superconductivity in ultrathin MoC films evidenced by STM measurements
• The unusual thickness dependence of superconductivity in $\alpha$-MoGe thin films
• Type II superconductivity in SrPd2Ge2

Cited by in corpus (4)

• Quantum breakdown of superconductivity in low-dimensional materials
• Superconductivity suppression in disordered films: Interplay of two-dimensional diffusion and three-dimensional ballistics
• Direct observation of intrinsic surface magnetic disorder in amorphous superconducting films
• Scanning tunneling spectroscopy of superconducting nitridized aluminum thin films