Superconducting weak bonds at grain boundaries in MgB2

Lomonosov Moscow State University, Moskva, Moscow, Russia
Journal of Experimental and Theoretical Physics (Impact Factor: 0.88). 10/2007; 105(3):636-641. DOI: 10.1134/S106377610709021X


The possibility of preparing bicrystalline Josephson junctions and bolometers based on superconducting MgB2 on specially prepared bicrystalline MgO substrates is investigated. Microbridges 0.85–6.00 μm in width, intersecting the
bicrystalline interface, are formed in epitaxial bicrystalline MgB2 films grown on these substrates. It is found that annealing of bicrystalline samples in oxygen leads to a systematic decrease
in the critical current, an increase in the temperature width of the superconducting transition region, and to an improvement
of the current-voltage (IV) characteristic, which becomes close in shape to the IV characteristic of a Josephson junction. The response of such a junction to radiation at a frequency of 110 GHz with an amplitude
attaining 0.5 mV is measured.

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