La2-xSrxCuOy epitaxial thin films (x=0 to 2): Structure, strain, and superconductivity

H. Sato, A. Tsukada, M. Naito, Azusa Matsuda

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Abstract

We have grown (001)-oriented thin films of La2-xSrxCuOy with strontium composition x=0-2 by reactive coevaporation and characterized them by x-ray-diffraction and resistivity measurements. A systematical change in the c-axis length indicates that single-phase films were obtained for the whole compositional range. The films with the oxygen composition y∼4 showed superconductivity for x between 0.06 and 0.30. For x =0.15, the superconducting transition temperature (Tc) was maximized to 44 K, due to a strain effect caused by the lattice mismatch between films and substrates. Around this composition, it is found that Tc for the films shows a good correlation with the c-axis length. For x=0.30, Tc for the films strongly depends on the residual resistivity [ρ(0 K)]: higher Tc for lower ρ(0 K). The depression of Tc around x=0.125 is smaller than that for the bulk samples, suggesting that the strain suppresses the "1/8 anomaly." The films with y>4 attained by cooling in ozone showed Tc between 40 and 48 K for x<0.15. For x>0.30, the compositional dependence of the resistivity is explained by both oxygen defects and a structural phase transition at x=1.8.

Original languageEnglish
Pages (from-to)12447-12456
Number of pages10
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume61
Issue number18
Publication statusPublished - 2000
Externally publishedYes

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ASJC Scopus subject areas

  • Condensed Matter Physics

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