Isovalent cation substitutions to control the intrinsic Hirr characteristics of superconductive copper oxides

M. Karppinen*, N. Kiryakov, Y. Yasukawa, T. Nakane, H. Yamauchi

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

7 Citations (Scopus)


The crucial role of the overall hole-doping level in controlling the magnetic irreversibility field (Hirr) values has been well documented for a number of copper-oxide superconductors. Here we show that not only the high overall hole-doping level but also the homogeneity of the hole distribution over the layered superconductive MmA2Qn-1CunOm+2+2n± δ or M-m(A)2(Q)(n-1)n crystal contributes to enhance the intrinsic Hirr characteristics. To control the homogeneity of the hole distribution, i.e. the distribution of holes (i) between the superconductive CuO2-(Q-CuO2)n-1 block and the non-superconductive AO-MmOm±δ-AO blocking block and (ii) within the superconductive CuO2-(Q-CuO2)n-1 block, isovalent cation substitutions are found effective. To demonstrate this, we summarize our studies on the effects of isovalent substitutions at Q and A sites on the Hirr characteristics of polycrystalline Cu(Ba,Sr)2RECu2O7-δ [Cu-1(Ba,Sr)2(RE)12] samples containing various "heavy rare earths" up to RE=Yb0.6Lu0.4 and Sr at the Ba site up to 40%, and also for single-crystal (Hg,Pb)(Ba,Sr)2Ca2Cu3O8+δ [(Hg,Pb)-1(Ba,Sr)2(Ca)23] samples with a Sr-for-Ba substitution level up to 75%.

Original languageEnglish
Pages (from-to)66-71
Number of pages6
Issue number1
Publication statusPublished - 15 Oct 2002
MoE publication typeA1 Journal article-refereed


  • Chemical pressure
  • Isovalent cation substitution
  • Magnetic irreversibility field

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