J. Phys. IV France
Volume 114, April 2004
Page(s) 367 - 369

J. Phys. IV France
114 (2004) 367
DOI: 10.1051/jp4:2004114085

Electrodynamics of molecular organic superconductors studied by $\mu
$ SR

F.L. Pratt1, 1, S.J. Blundell2, T. Lancaster2, S.L. Lee3 and N. Toyota4

1  ISIS Muon Facility, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX, UK
2  Clarendon Laboratory, Oxford University Department of Physics, Parks Road, Oxford OX3 3PU, UK
3  School of Physics and Astronomy, University of St. Andrews, St. Andrews, Fife KY16 9SS, UK
4  Department of Physics, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan

The response of the superconducting charge carriers to an applied magnetic field has been probed in a number of organic superconductors using $\mu
$SR. Systematic studies have been made of the in-plane superconducting penetration depth $\lambda $ in superconductors based on the ET and BETS molecules. These studies have revealed a strong correlation between $\lambda $ and T c. This type of correlation was first noted in high T c cuprates by Uemura et al who found a linear relation between T c and $\lambda ^{-2}$. In the case of organic superconductors, however, we find that the overall correlation is better described as T $_{c}\propto \lambda ^{-3}$. Understanding this characteristic trend should provide some important clues about the nature of the superconductivity in the organic superconductors; several possible models are considered here for describing this behaviour. It is concluded that models in which the superconducting carrier concentration is tied to the nominal band filling are inconsistent with the observed scaling behaviour. Key words. London penetration depth - Superconducting transition temperature.

© EDP Sciences 2004