Nanoscale physics

SQUIDs based on self-shunted MoRe-Si(W)-MoRe Josephson junctions
Shaternik V.E.1, Shapovalov A.P.2, Suvorov O.Yu.1, Kalenyuk A.A.1, Turutanov O.G.3, Lyakhno V.Yu.3, Febvre P.4, Shnyrkov V.I.2
1G.V. Kurdyumov Institute for Metal Physics, 36, Vernadsky bl., 03142 Kiev
E-mail: shaternikvolod@gmail.com. 
2Kyiv Academic University. 36, Vernadsky bl., 03142 Kiev
3B.Verkin Institute for Low Temperature Physics and Engineering.  47, Nauki av., 61103 Kharkov
4IMEP-LAHC, Université Savoie Mont Blanc, 73376 Le Bourget du Lac Cedex, France

The fundamental principles of operation of RF and DC SQUIDs using Josephson junctions shunted with normal metal resistor to eliminate hysterisis in current-voltage characteristics is already described in literature. However, to fabricate shunted SQUIDs and multi- SQUIDs systems with a good reproducibility of the main junctions parameters, one has to meet technological requirements. One of the promising ways is to replace externally shunted SIS junctions with self-shunted SNS junctions. Recently, direct experimental evidences have been obtained on the properties of Nb/α-Si/Nb and MoRe/α-Si(W)/MoRe [1] planar Josephson junctions with various degrees of doping of the amorphous silicon layer. These data reveal a reasonable agreement with classical resistive model for the SNS junction when the degree of doping is around 11%. In this work we concentrate our analysis on RF SQUID circuits based on MoRe/α-Si(W)/MoRe Josephson junctions having a d~10 nm thickness and a tungsten concentration in α-Si ~ 10%. Making the barrier thinner and reducing the doping would require nanoscale junctions and also dramatically compromise junction uniformity and multi-RF SQUID system reproducibility. It seems that properties of such junctions are crucially important from the point of view of realization of SQUID matrices, especially stochastic one.
S. V.E., S. A.P. and S. O.Yu. were supported by a joint Ukrainian-French grant from the MES of Ukraine.

1.	Shaternik V. E. et al. Charge Transport in Hybrid Tunnel Superconductor — Quantum Dot—Superconductor Junctions //IEEE Transactions on Applied Superconductivity. – 2017. – V. 27. – N. 4. – P. 1-7.