Doping-induced change of optical properties in underdoped cuprate superconductors

H. L. Liu*, M. A. Quijada, A. M. Zibold, Y. D. Yoon, D. B. Tanner, G. Cao, J. E. Crow, H. Berger, G. Margaritondo, L. Forró, O. Beom-Hoan, J. T. Markert, R. J. Kelly, M. Onellion

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

49 Citations (Scopus)


We report on the ab-plane optical reflectance measurements of single crystals of Y-doped Bi2Sr2CaCu2O8+∞ and Pr-doped YBa2Cu3O7-∞ over a wide frequency range from 80 to 40 000 cm-1 (10 meV-5 eV) and at temperatures between 20 and 300 K. Y and Pr doping both decrease the hole concentration in the CuO2 planes. This has allowed us to investigate the evolution of ab-plane charge dynamics at doping levels ranging from heavily underdoped to nearly optimally doped. Our results of the low-frequency optical conductivity and spectral weight do not show any features associated with the normal-state pseudogap. Instead, one-component analysis for the optical conductivity shows the low-frequency depression in the scattering rate at T > Tc, signalling entry into the pseudogap state. Alternatively, no clear indications of the normal-state pseudogap are detected in the temperature-dependent zero-frequency free-carrier scattering rate by using two-component analysis. In the superconducting state, there is also no convincing evidence of superconducting gap absorption in all spectra. We find that there is a 'universal correlation' between the numbers of carriers and the transition temperature. This correlation holds whether one considers the number of carriers in the superfluid or the total number of carriers.

Original languageEnglish
Pages (from-to)239-264
Number of pages26
JournalJournal of Physics Condensed Matter
Issue number1
Publication statusPublished - 1999
Externally publishedYes

ASJC Scopus subject areas

  • General Materials Science
  • Condensed Matter Physics


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