Abstract
We report on low-temperature scanning tunneling microscopy/spectroscopy experiments performed on superconducting boron-doped nanocrystalline diamond (NCD) thin films prepared by chemical-vapor deposition methods. The most representative sample reveals the observed superconducting gap highly modulated over a length scale on the order of , which is much shorter than the typical diamond grain size. The sample local and macroscopic behavior favors for the modulation as being an intrinsic property of the NCD granules. On the other hand, shows its temperature dependence consistent with the results obtained by Fominov and Feigel’man [Phys. Rev. B 63, 094518 (2001)], who studied theoretically the behavior of the superconducting gap of a BCS superconductor in contact with a normal layer by solving the one-dimensional Usadel equations on the superconducting side of the superconducting to normal interface.
- Received 19 January 2009
DOI:https://doi.org/10.1103/PhysRevB.80.224518
©2009 American Physical Society