Shubnikov–de Haas oscillations in the organic superconductor κ-(BEDT-TTF)2Cu[N(CN)2]Br, where BEDT-TTF is bis(ethylenedithio)tetrathiafulvalene

Magnetoresistance of the layered organic superconductor κ-(BEDT-TTF${)}_2$X with X=Cu[N(CN${)}_2$]Br has been studied under pressure up to ≊9 kbar. Prominent oscillations attributed to the Shubnikov–de Haas effect have been found at the highest pressure. The oscillation frequency corresponds to a Fermi-surface cylinder with its axis normal to the crystal highly conducting plane and cross section of 1.56×${10}^{14}$ ${\mathrm{cm}}^{\mathrm{-}2}$. The latter value is a factor of 4 smaller than that predicted by band-structure calculations for the ambient pressure.