Title: 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.