Oscillations of the interlayer resistance in the quasi-two-dimensional organic conductor image-(BEDT-TTF)2I3 under pressure

We measured both the temperature and the angular dependence of the interlayer resistance of the quasi-two-dimensional organic conductor β-(BEDT-TTF)2I3 under a hydrostatic pressure of 7 kbar. We observed the Shubnikov–de Haas oscillations similar to those observed at the ambient pressure after pressure–temperature cycling. The amplitude of the oscillations was greatly reduced with pressure, but the quasi-two-dimensional nature was preserved in spite of a five-fold decrease in transition temperature (Tc). While the fundamental frequency increased by 6.3%, the ratio of the modulation frequency to the fundamental frequency decreased by 11%. Pressure rendered the Fermi surface more two-dimensional.