K. D. Tsendin, D. V. Denisov, B. P. Popov, “Unified model of pseudogap features of conductivity in HTSCs”, Pis'ma v Zh. Èksper. Teoret. Fiz., 2004, Volume 80, Issue 4,Pages <nobr>277

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CONDENSED MATTER

Unified model of pseudogap features of conductivity in HTSCs

K. D. Tsendin^a, D. V. Denisov^a, B. P. Popov^b

^a Ioffe Physico-Technical Institute, Russian Academy of Sciences
^b Saint-Petersburg State Polytechnical University

Abstract: The pseudogap phenomenon in underdoped and optimally oxygen-doped high-temperature superconductors (HTSCs) of the Y₁Ba₂Cu₃O_x system is explained from a unified point of view within the model of negative U centers. It is shown that the pseudogap features of conductivity are not related directly to the superconductivity but arise due to the existence of statistical interaction of negative U centers with valence-band holes. Specifically due to this interaction, the hole density in the valence band does not remain constant. It differently changes with temperature for different mutual positions of the Fermi level and the valence band top. These differences lead to different temperature dependences of conductivity for underdoped and optimally doped samples.

PACS: 71.30.+h, 74.20.-z

Received: 06.04.2004
Revised: 15.06.2004