physica status solidi (a)
Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Editor: Stefan Hildebrandt (Editor-in-Chief), Sabine Bahrs (Deputy Editor)
Online ISSN: 1862-6319
Experimental Indications of a BCS Behaviour in Superconducting Diamond
This special issue of physica status solidi which was guest-edited by Satoshi Koizumi (National Institute for Materials Science, Tsukuba, Japan), Christoph E. Nebel (Diamond Research Center, Tsukuba, Japan), and Milos Nesladek (CEA-LIST, Gif sur Yvette, France) presents 10 Review Articles covering different areas of CVD Diamond research.
The cover picture was taken from the article by Sacépé et al. . The authors present a scanning tunneling spectroscopy study of superconducting single-crystalline heavily boron-doped diamond providing an experimental evidence for BCS behaviour. When a perpendicular magnetic field is applied to a superconducting boron-doped diamond film, vortices penetrate the sample, each carrying one quantum flux. In their centre, the superconductivity is washed out on a length scale equal to the superconducting coherence length ξs. The figures show the electronic Density of States (DOS) measured with a scanning tunnelling microscope at 50 mK along a line crossing the centre of a such a vortex. Outside the vortex core which extends between the two arrows, the DOS presents a gap at the Fermi level (V = 0) and two coherence peaks characteristic of a superconducting DOS. The measured DOS inside the vortex core reveals in addition numerous localized resonances, at positions pointed out by the black arrows on the two-dimensional view. For clean superconductors, quasi-particles are expected to form localized states inside the vortex cores at energies close to the Fermi level. Here, although boron-doped diamond films are in the dirty limit, localized resonances are still visible but at non zero energies inside the superconducting gap.