First observations of the heat capacity quantum oscillations in the organic superconductor (BEDT-TTF)(2)Cu(NCS)(2)

Specific heat measurements of a single crystal of the organic superconducto r (BEDT-TTF)(2)Cu(NCS)(2) have been carried out at temperatures 0.16 - 1 K and under magnetic field up to 20 T by the ac-method. For the first time th e heat capacity quantum oscillation (QO) was observed for this compound. Fr om the temperature and field dependencies of oscillation amplitude, we obta ined the dHvA frequency F = 622 T, the effective mass m(c)(*) = 3.3m(e) and the Dingle temperature X = 0.88 K. We did not detect any QO corresponding to the larger magnetic breakdown orbit. The Fermi surface curvature was est imated from the absolute value of the oscillation amplitude.