Evolution of optical absorption and superconductivity in Bi-2212 and 2223 oxides intercalated by metal-phthalocyanines. A systematical study as a function of intercalation level

L. Grigoryan, K. Yakushi, C. J. Liu, S. Takano, M. Wakata, H. Yamauchi

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Exposure to vapors of the metal-phthalocyanines MPc (M = Zn, Ni, Fe or Pb) brings about a systematical variation of optical and superconducting properties of Bi-2212 and 2223 high-Tc oxides. With increasing level of MPc uptake, the spectral weight is gradually transferred from the low to the high-frequency regions, accompanied by a decrease of Tc, diamagnetic response and magnetic hysteresis. Two different types of evolution patterns were observed: the first was characterized by a sharp change at the lowest level of MPc uptake (Tc, hysteresis), while the second featured a gradual evolution (intensities of the electronic absorption bands, diamagnetism). The heavily intercalated Bi-oxides are brightly colored non-conducting materials with well-resolved vibrational features due to both the intercalated MPc molecules and the host oxides. The above evolution patterns are ascribed to a combination of two mechanisms: the decrease of the charge carrier concentration as a result of electron doping into the host oxide, and the increase of anisotropy of the system due to incorporation of insulating MPc molecular layer between the Bi-O bilayers, thereby reducing the coupling along the c-axis. Hence, the intercalation by MPc is shown to be an effective technique for the electron doping leading to a reduction of the charge carrier concentration in the host oxides, in contrast to the intercalation by iodine which leads to a hole doping and to an increase of the number of charge carriers.

Original languageEnglish
Pages (from-to)153-163
Number of pages11
JournalPhysica C: Superconductivity and its applications
Issue number1-2
Publication statusPublished - 1993 Dec 1


All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering

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