Strong effect of crystal structure on the proximity effect between a superconductor and monolayer of cobalt

We present an unexpectedly strong influence of the proximity effect between bulk Ru(0001) superconductor and atomically thin layers Co on crystal structure latter. The monolayer grows in two different modifications, such as hcp stacking a reconstructed ε-like phase. While islands show weak little suppression superconductivity substrate next to it, more complex becomes almost fully superconducting. explain Ru rather abrupt jump superconducting order parameter by low transparency interface. In contrast, without phase indicates highly transparent This work highlights that normal metal strongly depends interface, which allows engineer hybrid structures.