Microwave Induced Steps in c-Axis YBa_2Cu_3O_7-x to Pb Josepshon Tunnel Junctions: Evidence for s-Wave Pairing Component of the High Tc Superconductor
Abstract
First-order Josephson tunneling through a YBCO-Pb tunnel junction grown on an a-b face of heavily twinned crystals or films of YBa_2Cu_3O_7-x (YBCO) is expected to cancel if the superconducting order parameter has pure d_x^2-y^2 symmetry; in this case, any residual Josephson current has to be second-order and the Josephson current-phase relationship has to be π-periodic. As a consequence, microwaves at frequency f will induce steps on the current-voltage characteristic at voltages that are multiples of hf/4e. Experimentally, we observed steps only at multiples of hf/2e. The result strongly suggests that s-wave pairing is present in YBCO; however, the simultaneous presence of d-wave pairing is by no means ruled out.
- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- March 1996
- Bibcode:
- 1996APS..MAR.O1002K