YBa 2Cu 3O 7− x thin-film Josephson junctions on 2 × 12° bicrystal (110) NdGaO 3 substrates

Abstract

Grain-boundary YBa 2Cu 3O 7− x Josephson junctions with normal-state resistances from 0.1 to 10 Ω were fabricated on (110) NdGaO 3 bicrystal substrates with a misorientation angle of 2 × 12°. Electrical imaging of the junctions in the temperature range 80 K–300 K was performed by a technique based on laser scanning microscopy. The average values of the electrical transport parameters of the fabricated junctions were shown to be comparable to those of reference junctions made on (100) SrTiO 3 bicrystals. Values of the Josephson linewidth as low as 1 GHz at 77 K have been obtained from the response of the junctions to low-intensity 94 GHz electromagnetic radiation. When high-intensity 94 GHz radiation was applied to the junctions, current steps appeared in the I–V curves at voltages V n = n hf/2 e up to 6.5 mV. These results demonstrate the applicability of YBa 2Cu 3O 7− x grain-boundary junctions made on NdGaO 3 bicrystal substrates for millimeter- and submillimeter-wave detection.