Scanning tunneling spectroscopy of SmFeAsO0.85 : Possible evidence for d -wave order-parameter symmetry
Abstract
We report a scanning tunneling spectroscopy investigation of polycrystalline SmFeAsO0.85 having a superconducting transition at 52 K. On large regions of the sample surface the tunneling spectra exhibited V -shaped gap structures with no coherence peaks, indicating degraded surface properties. In some regions, however, the coherence peaks were clearly observed and the V -shaped gaps could be fitted to the theory of tunneling into a d -wave superconductor, yielding gap values between 8 and 8.5 meV corresponding to the ratio 2Δ/KBTC∼3.55-3.8 , which is slightly above the BCS weak-coupling prediction. In other regions the spectra exhibited zero-bias conductance peaks consistent with a d -wave order-parameter symmetry.
- Publication:
-
Physical Review B
- Pub Date:
- September 2008
- DOI:
- 10.1103/PhysRevB.78.092505
- arXiv:
- arXiv:0807.0359
- Bibcode:
- 2008PhRvB..78i2505M
- Keywords:
-
- 74.50.+r;
- 74.70.-b;
- Tunneling phenomena;
- point contacts weak links Josephson effects;
- Superconducting materials;
- Condensed Matter - Superconductivity
- E-Print:
- Phys. Rev. B 78, 092505 (2008)