Data from ab-oriented YBa2Cu3O7/I/Cu tunnel junctions are presented. Self-assembled monolayers form the insulating tunnel barrier. I. The YBa2Cu3O7 features in the tunneling conductance match those of low-leakage ab-oriented YBa2Cu3O7/Pb junctions. Results show that the zero-bias conductance peak is an Andreev bound state (ABS) of a d-wave order parameter. In zero magnetic held, the ABS splits below ∼7 K, consistent with the presence of a subdominant order parameter at the surface. An applied magnetic held induces further splitting that grows nonlinearly with increasing field.
ASJC Scopus subject areas
- Physics and Astronomy(all)