Pseudogap induced by superconducting fluctuation and anomalous metals in high-T-c superconducting materials

Citation
A. Kobayashi et al., Pseudogap induced by superconducting fluctuation and anomalous metals in high-T-c superconducting materials, J PHYS CH S, 62(1-2), 2001, pp. 69-74
Citations number
33
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science
Journal title
JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS
ISSN journal
0022-3697 → ACNP
Volume
62
Issue
1-2
Year of publication
2001
Pages
69 - 74
Database
ISI
SICI code
0022-3697(200101/02)62:1-2<69:PIBSFA>2.0.ZU;2-R
Abstract
The pseudogap in the single particle spectrum induced by the superconductin g fluctuation together with the antiferromagnetic spin fluctuation has been believed to play key roles to determine essential features of anomalous pr operties of Cu-oxide high-T-c superconducting materials observed at tempera tures higher than the superconducting transition temperature T-c. The roles are described as follows: in metals near Mott insulators, doped holes crea te new states inside the charge transfer gap called as ingap states, which have band width proportional to the hole doping rate delta and interact wit h each other through the superexchange interaction J(s) enhanced by the ant iferromagnetic spin fluctuation. This effective interaction promotes super conducting fluctuation, which induces a pseudogap in the single particle sp ectra. On the other hand. the pseudogap suppresses the spin fluctuation. Th us. effects of both of the spin fluctuation and the superconducting fluctua tion need to be treated in a consistent way. In an underdoped system. the s pin fluctuation dominates at higher temperatures. while the superconducting fluctuation or the pseudogap effect dominates at lower temperatures above T-c. This competition determines the anomalous temperature dependence of sy stems. We demonstrate the senario explicitly by taking the d-p model with t he help of the 1/N-expansion theory and calculating T-c, the NMR relaxation rate 1/T-I and the single-particle spectrum. (C) 2000 Elsevier Science Ltd . All rights reserved.