Theory of Josephson tunneling along the c-axis of YBCO

Robert Haslinger; Robert Joynt

paper

Theory of Josephson tunneling along the c-axis of YBCO

arXiv:cond-mat/9803124

Abstract

The existence of Josephson tunneling has been demonstrated between YBa $_{2}$ Cu $_{3}$ O $_{7 - δ}$ and Pb with the current flowing along the c-axis of YBa $_{2}$ Cu $_{3}$ O $_{7 - δ}$ . This is presumed to come from an s-wave component of the superconductivity in YBa $_{2}$ Cu $_{3}$ O $_{7 - δ}$ , perhaps induced by the orthorhombic distortion. This hypothesis by itself appears to be in contradiction with experiments on twinned samples whose tunneling current does not follow random statistics. We present a theory which depends on a competition between the intertwin d-wave coupling and a relatively enhanced s-wave component on the surface. This theory appears to explain, at least qualitatively, all observations made to date.

3 pages revtex, 4 eps figures