ab-plane optical properties of Ni-doped Bi2Sr2CaCu2O8+δ

H. L. Liu*, D. B. Tanner, H. Berger, G. Margaritondo


研究成果: 雜誌貢獻期刊論文同行評審

6 引文 斯高帕斯(Scopus)


The ab-plane optical reflectance of single crystal of Bi2Sr2Ca(Cu1-xNix)2O 8+δ, for x=0.0215, has been measured from 80 to 40000 cm-1 (10 meV-5 eV) and at temperatures between 20 and 300 K. Through Ni substitution, the optical conductivity shows a broad peak at about 400 cm-1, which grows in intensity and shifts to lower frequency as the temperature is reduced. We suggest that this peculiar low-frequency feature is associated with the significant disorder induced by Ni impurities. Analysis of the conductivity within the framework of the two-component and the one-component pictures indicates that the main effect of Ni substitution is to increase impurity scattering rate. There is no evidence of a rapid drop in the free carrier scattering rate near Tc. An estimate of the low-frequency spectral weight shows that Ni reduces the carrier density in the CuO2 plane: each Ni removes one carrier. Below Tc, a sum-rule evaluation finds the superconducting condensate contains about a fifth of the total doping-induced, or two thirds of the free-carrier oscillator strength in the normal state. The strength of the condensate is horizontally offset from the Uemura line, with a smaller superfluid density than implied by Tc. This decreased superfluid density in the CuO2 plane could be connected with the effect of impurity-induced disorder.

頁(從 - 到)197-210
期刊Physica C: Superconductivity and its applications
出版狀態已發佈 - 1999

ASJC Scopus subject areas

  • 電子、光磁材料
  • 凝聚態物理學
  • 能源工程與電力技術
  • 電氣與電子工程


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