OXYGEN IN THE POSSIBLE ROLE OF MEDIATOR OF PAIRING

For an oxygen atmosphere it has been pointed out that even in conventi onally prepared YBa2Cu3O6+x samples T-c may be increased. In addition, resistivity versus temperature curves exhibit anomalies when the samp les have been annealed in oxygen at 343 K for sufficiently long time. This effect is distinguished from the increase of T-c when illuminated with a laser beam. An explanation of this effect has been suggested w ithin Jansen-Block model of indirect exchange pairing via oxygen atoms .