Quasi-two-dimensional Fermi surfaces and the de Haas-van Alphen oscillation in both the normal and superconducting mixed states of CeCoIn5

We observed de Haas-van Alphen (dHvA) oscillation in both the normal and superconducting mixed states of a heavy-fermion superconductor CeCoIn5. The Fermi surfaces are found to consist of nearly cylindrical Fermi surfaces and small ellipsoidal ones, reflecting the unique tetragonal crystal structure. The detected cyclotron masses of 5-87 m(0) for these Fermi surfaces are extremely large, and correspond to a large electronic specific heat coefficient of about 1000 mi K-2 mol(-1). The cyclotron masses are also found to be field dependent in both the normal and mixed states.