Observation of “saw-tooth” de Haas-van alphen oscillation in a two-dimensional organic superconductor θ-(BEDT-TTF)2I3

A “saw-tooth” de Haas-van Alphen oscillation was observed in an organic superconductor θ-(BEDT-TTF)2I3 under the magnetic field H>15 T at T=0.5 K. The fundamental frequency of the oscillation (H0=4170 T) corresponds to the closed Fermi surface area of 50% of the first Brillouin zone, consistent with one positive charge carrier per I3- anion. An issue about the Fermi surface topology is resolved based on the analysis of the dH-vA oscillation frequencies. The “saw-tooth” variation of magnetization demonstrates that organic metals can provide an ideal example of highly two-dimensional and extraordinary clean electron system with a cylindrical Fermi surface along the direction perpendicular to the conducting plane.