Fermi Surface Properties in CeCo₂

Abstract

We have succeeded in oberving the de Haas-van Alphen (dHvA) effect in the mixed valent superconductor CeCo₂. The detected dHvA frequencies range from 6.24× 10⁵ Oe to 8.77× 10⁷ Oe. The largest frequency branch shows almost no angular dependence, indicating a nearly spherical Fermi surface. The cyclotron effective masses are found to be highly enhanced compared to the free-electron mass m_0, ranging from 0.97 m_0 to 10.9 m_0. The magnetoresistance measurements gives an evidence that the Fermi surface sheets are all closed without any open orbits. Band structure calculation based on a relativistic linear augmented-plane-wave (RLAPW) method, assuming the 4f electrons as itinerant, is in reasonably good agreement with the experimental dHvA results.