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Crystallinity, exchange-correlation and isotope effects on the plasmon excitations in high Tc superconductors

Journal Article


Abstract


  • With the use of a tight-binding model the authors have studied the effects due to crystallinity, i.e. the atomic structure, of the Cu-O2 planes and Cu-O chain planes of the high-Tc superconductors on the intralayer and interlayer Coulomb interactions as well as the density-density response function. This effect is found to be appreciable since each electron is well localized around the copper site and the size of the unit cell is comparable with the lattice constant. Localization leads to poor conductivity in the normal state and is determined by the hopping between adjacent copper sites caused by the overlap of electron wavefunctions with electrons on the oxygen site. The dominant local exchange-correlation contribution is included in the local-field approximation. By taking account of the plasmon-optical phonon coupling in their calculations, the authors have demonstrated the isotope effect for acoustical plasmon-mediated pairing as well as the effect on the effective intralayer Coulomb interaction which is believed to be important for the formation of Cooper pairs in the Cu-O2 planes. The effects due to the position of the chain planes and the number of planes in each unit cell on the plasmon excitation energies as well as the effective intralayer Coulomb interaction are also studied. The relationship between these effects and the critical temperature Tc is discussed.

Publication Date


  • 1992

Citation


  • Huang, D., Zhang, C., & Gumbs, G. (1992). Crystallinity, exchange-correlation and isotope effects on the plasmon excitations in high Tc superconductors. Journal of Physics: Condensed Matter, 4(13), 3533-3550. doi:10.1088/0953-8984/4/13/016

Scopus Eid


  • 2-s2.0-36149034385

Start Page


  • 3533

End Page


  • 3550

Volume


  • 4

Issue


  • 13

Abstract


  • With the use of a tight-binding model the authors have studied the effects due to crystallinity, i.e. the atomic structure, of the Cu-O2 planes and Cu-O chain planes of the high-Tc superconductors on the intralayer and interlayer Coulomb interactions as well as the density-density response function. This effect is found to be appreciable since each electron is well localized around the copper site and the size of the unit cell is comparable with the lattice constant. Localization leads to poor conductivity in the normal state and is determined by the hopping between adjacent copper sites caused by the overlap of electron wavefunctions with electrons on the oxygen site. The dominant local exchange-correlation contribution is included in the local-field approximation. By taking account of the plasmon-optical phonon coupling in their calculations, the authors have demonstrated the isotope effect for acoustical plasmon-mediated pairing as well as the effect on the effective intralayer Coulomb interaction which is believed to be important for the formation of Cooper pairs in the Cu-O2 planes. The effects due to the position of the chain planes and the number of planes in each unit cell on the plasmon excitation energies as well as the effective intralayer Coulomb interaction are also studied. The relationship between these effects and the critical temperature Tc is discussed.

Publication Date


  • 1992

Citation


  • Huang, D., Zhang, C., & Gumbs, G. (1992). Crystallinity, exchange-correlation and isotope effects on the plasmon excitations in high Tc superconductors. Journal of Physics: Condensed Matter, 4(13), 3533-3550. doi:10.1088/0953-8984/4/13/016

Scopus Eid


  • 2-s2.0-36149034385

Start Page


  • 3533

End Page


  • 3550

Volume


  • 4

Issue


  • 13