J. Phys. IV France 114 (2004) 277
DOI: 10.1051/jp4:2004114058

Fermi-surface reconstruction close to a pressure-induced metal-insulator transition

J. Wosnitza¹, J. Hagel¹, O. Stockert², C. Pfleiderer³, J.A. Schlueter⁴, J. Mohtasham⁵ and G.L. Gard<sup>5

1</sup>  Institut für Festkörperphysik, Technische Universität Dresden, 01062 Dresden, Germany
    e-mail: Wosnitza@physik.tu-dresden.de
²  MPI Chemische Physik fester Stoffe, 01187 Dresden, Germany
³  Physikalisches Institut, Universität Karlsruhe, 76128 Karlsruhe, Germany
⁴  Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
⁵  Department of Chemistry, Portland State University, Portland, Oregon 97207, USA

Abstract
We report on a detailed investigation of the pressure-dependent structural and electronic properties close to the pressure-induced metal-insulator transition of the quasi-two-dimensional organic superconductor -(BEDT-TTF) ₂SF ₅CH ₂CF ₂SO ₃, where BEDT-TTF stand for bisethylenedithio-tetrathiafulvalene (or ET for short). Although the pressure-dependent hysteresis of the metal-insulator transition suggests a structural origin, no major crystallographic modifications could be detected by neutron-scattering experiments. Shubnikovde Haas (SdH) experiments, on the other hand, show that a reconstructed band structure precedes the phase transition to the insulating state. A new SdH frequency with a rather small effective mass appears. Key words. organic superconductors band structure metal-insulator transition.

© EDP Sciences 2004