Detailed characterization of U-Co binary compounds

Matsuda, Tatsuma; Sugai, Takashi; Haga, Yoshinori   ; Yamamoto, Etsuji  ; Onuki, Yoshichika

For U-Co binary systems, at least 6 stable phases were reported previously. These systems show a variety of physical properties. UCo and UCo exhibit superconductivity. Furthermore, the possible crystal structural model without inversion symmetry was proposed by analyses of X-ray powder diffractions. Recently, single crystals of UCo are succeeded to grow by the Czochralski pulling method. For comparison, polycrystalline sample was also prepared by arc melting. Below 2 K, the both samples showed zero resistivity as reported earlier. We also checked the composition of these crystals by electron probe micro analyzer (EPMA) and took the pictures of scanning SEM image. We confirmed the existence of a small amount of uranium-rich 2nd phase in these crystals. Considering these results, it can be suggested that the uranium-rich 2nd phase corresponds to UCo.