2003/05/31 by Guang‐Han Cao, Guanghan Cao, Hideaki Kitazawa +2 · 1 citation
Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Magnetic and transport properties of perovskites and related materials #Physics of Superconductivity and Magnetism #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.69.045106
published as Phys. Rev. B 69, 045106 (2004) · 7 pages, 9 figures
arxiv created 2003/12/05 · openalex publication_date 2004/01/15 · arxiv updated 2009/11/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
The pseudobinary thiospinel system Cu_1\ensuremath-xCdxIr2S4 was investigated by the x-ray-diffraction, electrical resistivity, magnetic-susceptibility, and specific-heat measurements. It was shown that the system exhibits a miscibility-gap behavior for the Cd substitution, however, nearly monophasic samples were obtained by quenching at 1373 K, except for 0.4<x<~0.6. With increasing the Cd concentration, the room-temperature electrical conductivity and Pauli susceptibility decrease monotonically, consistent with the hole-filling picture. The first-order metal-insulator transition at about 230 K in the parent compound CuIr2S4 is changed into a second-order transition around 185 K when x\ensuremath∼0.25, whereafter the second-order transition disappears at x\ensuremath∼0.8. No superconductivity was observed down to 1.8 K. The end-member compound CdIr2S4 is shown as an insulator with a band gap of 0.3 eV. Analysis for the data of magnetic susceptibility and electrical resistivity suggests the formation of bipolarons below 185 K for 0.25<x<0.8, which accounts for the absence of superconductivity in terms of the transition from the BCS Cooper pairs to small bipolarons.