Nanoscale physics

Josephson effect in superconducting junctions with a semiconducting barrier containing metallic nanoclusters
Kasatkin A.L.1, Shaternik V.E.1, Suvorov O.Yu.1, Shapovalov A.P.2
1G.V. Kurdyumov Institute for Metal Physics, 36, Vernadsky bl., 03142 Kiev
E-mail: al_kas@i.ua
2V. Bakul Institute for Superhard Materials, 2, Avtozavods’ka str., 07074 Kyiv

The modern trend in development of superconducting electronics requires new technological approaches to the fabrication of Josephson junctions. One of these approaches is related with the usage of a semiconductor layer as weak linkage between superconducting layers. This can provide definite advantages (such as low capacity, high characteristic voltages JcRn, etc.) of such kind Josephson junctions comparatively to that traditionally used, e.g. S-I-S or S-N-S junctions [1].
In this work we present our results on the Josephson effect in a new type of Josephson junction MoRe-Si(W)-MoRe containing nanoclusters of the normal metal (W) inside the rather thick (~15 nm) semiconductor middle layer (Si) inserted  between the deposited on its both sides superconducting films MoRe [2]. These W-nanoclasters, starting from some threshold concentration nw,c, can form continuous links like nanobridges or resonance-percolation trajectories and thus provide the Josephson effect. We explored experimentally the concentration (nw),  temperature and magnetic field H dependencies of the Josephson critical current Jc for this type junctions and found its rather interesting and useful for applications feature, namely: unusually weak dependence Jc(H) (in form of some background Jc0 perturbed by weak oscillations on H value). The corresponding theoretical model which can explain observed Jc(H) for this type junctions was elaborated.
The work was supported by Targeted Research & Development Initiatives Programme funded by the STCU and the National Academy of Science of Ukraine (Project No. 6250). 

1.	Gudkov A. L., Kupriyanov M. Yu., Samus’ A. N. Properties of Planar Nb/α-Si/Nb Josephson Junctions with Various Degrees of Doping of the α-Si Layer // JETP.- 2012.-114, N 5.-P. 818–829.
2.	Shaternik V.E., Shapovalov A.P., Suvorov O.Yu.. Charge transport in superconducting MoRe–Si(W)–MoRe heterostructures with hybrid semiconductor barrier containing metal nanoclusters // Low Temp. Phys. -2017.- 43, N 7.-P. 877-881.