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arXiv · 1701.02320

Ion-irradiated YBa$_2$Cu$_3$O$_7$ Josephson arrays

A. Sharafiev·M. Malnou·C. Feuillet-Palma·C. Ulysse·P. Febvre·J. Lesueur·N. Bergeal
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Abstract

We designed, fabricated and tested short one dimensional arrays of masked ion-irradiated YBa$_2$Cu$_3$O$_7$ Josephson junctions (JJ) embedded into log-periodic spiral antennas. Our arrays consist of 4 or 8 junctions separated either by 960~nm or 80~nm long areas of undamaged YBCO. Samples with distanced junctions and with closely spaced junctions showed qualitatively different behaviors. Well separated arrays demonstrated giant Shapiro steps in the hundreds-GHz band at 66K and were tested as Josephson mixers with improved impedance matching. All closely spaced arrays behaved as one junction with a lower superconducting transition temperature, hence forming a single weak link on distances up to 880~nm. Such design opens a new way to increase the I$_{c}$R$_{N}$ product of ion-irradiated junctions and we speculate that the phenomena and physics behind it might be similar to the so-called "giant" Josephson coupling observed in cuprates.

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A. Sharafiev, M. Malnou, C. Feuillet-Palma, C. Ulysse, P. Febvre, J. Lesueur, N. Bergeal. 2017-01-09. Ion-irradiated YBa$_2$Cu$_3$O$_7$ Josephson arrays. https://arxiv.org/abs/1701.02320

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