Theory of Bi2Sr2CaCu2O8+δ cross-whisker Josephson junctions -: art. no. 174509

Takano [Phys. Rev. B 65, 140513 (2002); J. Low Temp. Phys. 131, 533 (2003)] made Josephson junctions from single crystal whiskers of Bi2Sr2CaCu2O8+delta crossed an angle phi(0) about the c axis. From the mesa structures that formed at the cross-whisker interface, they inferred a critical current density J(c)(phi(0)). As with the single crystal results of Li et al. [Phys. Rev. Lett. 83, 4160 (1999)], we show that the whisker data are unlikely to result from a predominantly d-wave order parameter. However, unlike the single crystals, these results, if correct, require the whisker c-axis transport to be coherent.