Anomalous x dependence of Tc and possibility of low-temperature structural phase transition in La2-xSrxCu0.99M0.01O4 (M Ni, Zn, Ga)

Y. Koike, A. Kobayashi, T. Kawaguchi, M. Kato, T. Noji, Y. Ono, T. Hikita, Y. Saito

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Effects of the 1% substitution of Ni, Zn and Ga for Cu on the x dependence of Tc have been investigated in La2-xSrxCuO4. The Tc increases by the Cu-site substitution in all compositions of x. The local minimum of Tc as a function of x, appearing slightly near x = 0.115 for La2-xSrxCuO4, becomes conspicuous with decreasing Tc. However, structural phase transition from the orthorhombic mid-temperature phase to the tetragonal low-temperature phase has not been detected from powder X-ray diffraction measurements at low temperatures down to 12 K. The local minimum of Tc is attributable to the fluctuation of the undiscovered structural phase transition, which will occur at a low temperature below 12 K as long as samples are in the normal-conducting state. In the 1% Ga-substituted system for Cu, the local minimum clearly shifts from x = 0.115 to 0.125. This suggests that the undiscovered low-temperature structural phase transition is due to the optimum hole concentration of 0.115 per Cu atom, analogously to La2-xBaxCuO4.

Original languageEnglish
Pages (from-to)889-893
Number of pages5
JournalSolid State Communications
Issue number11
Publication statusPublished - 1992 Jun

ASJC Scopus subject areas

  • Chemistry(all)
  • Condensed Matter Physics
  • Materials Chemistry


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