Tl‐Ca‐Ba‐Cu‐O step‐edge Josephson junctions Available to Purchase

There has been considerable progress in the development of nonhysteretic Josephson junction microelectronic technologies for YBaCuO. Such a technology for Tl‐Ca‐Ba‐Cu‐O junctions would be interesting because of the higher operating temperatures and the very different grain boundary structures in the different cuprate superconductors. We have successfully made step‐edge junctions with TlCaBaCuO grown on ion‐milled LaAlO₃. Nonhysteretic grain boundary‐based junctions have been demonstrated with critical current‐normal state resistance products exceeding 5 mV at 77 K, critical current densities ranging from 500 to 25 000 A/cm², and critical current versus field profiles suggesting very uniform junctions. Yield has exceeded 70% on over 250 junctions tested and operation has been demonstrated to 100 K.