arXiv subjects
Publications and source records attributed to Ryusuke Kondo.
We report a reproducible synthetic method for superconducting Cu-intercalated Bi2Se3 by an improved melt growth method. Avoiding the production of Cu2Se, which has a higher melting point than that of Bi2Se3, and quenching Cu-Bi-Se mixtures at the liquid phase are keys to obtaining good superconducting samples in a reproducible manner.
We investigate bulk superconductivity in a high-quality single crystal of Bi$_2$Pd ($β$-Bi$_2$Pd, space group; I4/mmm) at temperatures less than 5.4 K by exploring its electrical resistivity, magnetic susceptibility, and specific heat. The temperature dependence of the electrical resistivity shows convex-upward behaviors at temperatures greater than 40-50 K, which can be explained by a parallel-resistor model. In addition, we demonstrate that this material is a multiple-band/multiple-gap superconductor based on the temperature dependences of the specific heat and the upper critical field.
We have studied the crystal structure and magnetic properties of the organic radical cation salt, BBDTA-InCl4. This material formed a one-dimensional coordination polymer, whose structure was characteristic of inorganic spin-Peierls materials. Magnetic measurements indicated the spin-Peierls transition like behavior at 108 K, which was higher than those typically observed for the other organic spin-Peierls materials. The structural aspects of the lattice distortion from X-ray diffraction measurements at 50 K have been discussed.