Enhancement of superconducting temperature of Nb thin film via linking of Au nanoparticles
Wan Ju Li1, Sung Po Chao1*
1Institute of Physics, Academia Sinica, Taipei, Taiwan
* presenting author:Sung Po Chao, email:spchao@gmail.com
The superconducting critical temperature, Tc, of Nb thin films is modified when gold nanoparticles (Au NPs) are chemically linked to the Nb film [1]. With longer linker molecules Tc is found to increase up to 10%, while for shorter or nonlinking linker Tc is smaller than that of bare Nb film. STM measurement shows zero bias peak in Au NPs in samples exhibiting Tc enhacement, and gapped density of state is found in Au NPs in samples showing decreasing Tc, consistent with the usual proximity effect. Motivated by this experiment, we propose a theoretical model to see how the impurities modify the Tc, and suggest the key mechanism of Tc enhancement is related to the impurities pinning of vortices in this type II superconductor.

[1] E Katzir et. al., Phys. Rev. Lett. 108, 107004 (2012)

Keywords: superconductivity, Kosterlitz Thouless transition, proximity effect