Admixtures to d-wave gap symmetry in untwinned YBa2Cu3O7 superconducting films measured by angle-resolved electron tunneling

H J H Smilde; A A Golubov; Ariando; G Rijnders; J M Dekkers; S Harkema; D H A Blank; H Rogalla; H Hilgenkamp

doi:10.1103/PhysRevLett.95.257001

Admixtures to d-wave gap symmetry in untwinned YBa2Cu3O7 superconducting films measured by angle-resolved electron tunneling

Phys Rev Lett. 2005 Dec 16;95(25):257001. doi: 10.1103/PhysRevLett.95.257001. Epub 2005 Dec 12.

Authors

H J H Smilde¹, A A Golubov, Ariando, G Rijnders, J M Dekkers, S Harkema, D H A Blank, H Rogalla, H Hilgenkamp

Affiliation

¹ Faculty of Science and Technology and Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.

PMID: 16390254
DOI: 10.1103/PhysRevLett.95.257001

Abstract

We report on an ab anisotropy of Jc parallel b/Jc parallel a approximately/= 1.8 IcRn parallelb/IcRn parallel a approximately/= 1.2 and in ramp-edge junctions between untwinned YBa2Cu3O7 and s-wave Nb. For these junctions, the angle theta with the YBa2Cu3O7 crystal b axis is varied as a single parameter. The RnA(theta) dependence presents twofold symmetry. The minima in IcRn at theta approximately/= 50 degrees suggest a real s-wave subdominant component and negligible d(xy)-wave or imaginary s-wave admixtures. The IcRn(theta) dependence is well fitted by 83% dx2-y2-, 15% isotropic s-, and 2% anisotropic s-wave order parameter symmetry, consistent with deltab/deltaa approximately/= 1.5.