Electronic structure and properties of the high-Tc superconductors

Tl2Ba2CaCu2O8 and Tl2Ba2Ca2Cu3O10

Jaejun Yu, S. Massidda, Arthur J Freeman

Research output: Contribution to journalArticle

108 Citations (Scopus)

Abstract

We present results of highly precise local density calculations of the electronic structure of the two high-Tc superconductors Tl2Ba2CaCuO8 (Tc≅112 K) and Tl2Ba2Ca2Cu3O10 (Tc≅125 K), as obtained with the full potential linearized augmented plane wave (FLAPW) method. A relatively simple band structure is found near EF and strong 2D properties are predicted. Again as in the case of the other high-Tc materials, Ba and Ca are highly ionic, with the Ca2+ ions insulating the Cu-O planes. The Tl-O complexes, which are decoupled from the Cu-O planes, produce small electron pockets at EF with predominant O character that contribute to the transport properties. Each Cu-O plane is found to contribute ≃ 1 state/(eV-Cu atom) to the density of states (DOS) at EF, similar to the Bi2Sr2CaCu2O8 case. Remarkable strong fermi surface nesting is found along the (100) and (010) directions for the 2D Cu-O dpσ bands. Significantly, we show that the usual simple nearest-neighbors only tight-binding model cannot properly describe these states. Crude rigid ion calculations show that a purely electron-phonon mechanism is inadequate to explain the observed high Tc. As in the case of the other high-Tc superconductors, a charge transfer excitation (excitonic) mechanism appears likely. Interestingly, the partial DOS structure shows that both systems can be viewed as a metal-semiconductor (or metal-semimetal) superlattice indicating a possible relation to the Allender, Bray, and Bardeen model of excitonic superconductivity.

Original languageEnglish
Pages (from-to)273-282
Number of pages10
JournalPhysica C: Superconductivity and its Applications
Volume152
Issue number4
DOIs
Publication statusPublished - Jun 1 1988

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Electronic properties
Superconducting materials
Electronic structure
Metals
Ions
electronic structure
Metalloids
Fermi surface
Electrons
Superconductivity
Band structure
Transport properties
Charge transfer
metalloids
Semiconductor materials
Atoms
metals
Fermi surfaces
ions
plane waves

ASJC Scopus subject areas

  • Condensed Matter Physics

Cite this

Electronic structure and properties of the high-Tc superconductors : Tl2Ba2CaCu2O8 and Tl2Ba2Ca2Cu3O10. / Yu, Jaejun; Massidda, S.; Freeman, Arthur J.

In: Physica C: Superconductivity and its Applications, Vol. 152, No. 4, 01.06.1988, p. 273-282.

Research output: Contribution to journalArticle

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