Thermal activation between Landau levels in the organic superconductor beta ''-(BEDT-TTF)(2)SF5CH2CF2SO3 - art. no. 117001

We show that Shubnikov-de Haas oscillations in the interlayer resistivity o f the organic superconductor beta"-(BEDT-TTF)(2)SF5CH2CF2SO3 become very pr onounced in magnetic fields similar to 60 T. The conductivity minima exhibi t thermally activated behavior that can be explained simply by the presence of a Landau gap, with the quasi-one-dimensional Fermi surface sheets contr ibuting negligibly to the conductivity. This observation, together with com plete suppression of chemical potential oscillations, is consistent with an incommensurate nesting instability of the quasi-one-dimensional sheets.