Physical Properties of SuperconductivityNo Access

STRUCTURE AND SUPERCONDUCTIVITY OF GaSr₂(Tm,Ca)Cu₂O_z CUPRATE DOPED WITH COBALT

H. K. LEE

Department of Physics, Kangwon National University, Chuncheon 200-701, Republic of Korea

Korea Basic Science Institute, Chuncheon Center, Chuncheon 200-701, Republic of Korea

Corresponding author.

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and

Y. I. KIM

Korea Research Institute of Standards and Science, P.O.Box 102, Yusong, Daejeon 305-606, Republic of Korea

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https://doi.org/10.1142/S0217979207044214Cited by:1 (Source: Crossref)

Abstract

To address the structural mechanisms associated with T_c variations induced by Co doping, two samples of the nominal composition (Ga_1-xCo_x)Sr₂(Tm_0.6Ca_0.4)Cu₂O_z with x = 0.5 and 0.7 have been prepared and studied by using neutron powder diffraction and transport measurements. In contrast to the x = 0.5 sample, which shows superconductivity around 35 K, the x = 0.7 sample does not exhibit superconductivity. The neutron powder diffraction studies indicate that both samples exhibit the 1212 structure with space group Ima2 and the Co atoms exclusively substitute for the Cu atoms located on the chain sites of the 123 parent structure. The depression in Tc of the x = 0.7 sample, compared to that of the x = 0.5 sample, is discussed in connection with oxygen content, disorder, and change in hole concentration on the superconducting planes.