Fermi surface properties and de Haas-van Alphen oscillation in both the normal and superconducting mixed states of URu2Si2

We have succeeded in growing a high-quality single crystal of URu2Si2 with a residual resistivity ratio of 255 and performed magnetoresistance and de Haas-van Alphen (dHvA) experiments. The dHvA oscillations were observed cle arly in both the normal and superconducting mixed states. From the magnetor esistance experiments, it is concluded that URu2Si2 is a compensated metal with equal carrier numbers of electrons and holes. In the dHvA experiments we observed three kinds of Fermi surfaces. We studied precisely the Fermi s urface properties in both the normal and mixed states. The dHvA frequency d oes not change in magnitude between the normal and mixed states, while the cyclotron effective mass is reduced, and the corresponding Dingle temperatu re or scattering rate of the conduction electron increases in the mixed sta te.