### Abstract

It is shown that the square-root van Hove singularity appearing in the density of states ?(E_{F})~(E_{F}-E_{0})^{-1/2} as a result of extended saddle-point singularities in the electron spectrum of high-T_{c} superconductors based on hole-type cuprate metal-oxide compounds gives a nonmonotonic dependence of the critical temperature T_{c} on the position of the Fermi level E_{F} relative to the bottom E_{0} of the saddle. Because the divergence of ?(E_{F}) is canceled in the electron-electron interaction constant renormalized by strong-coupling effects, T_{c} approaches zero as E_{F}?E_{0}, in contrast to the weak-coupling approximation, where in this limit T_{c} approaches a finite (close to maximum) value. The dependence obtained for T_{c} as a function of the doped hole density in the strong-coupling approximation agrees qualitatively with the experimental data for overdoped cuprate metal oxides. © 1998 American Institute of Physics.

Original language | English |
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Pages (from-to) | 495-500 |

Number of pages | 6 |

Journal | JETP Letters |

Volume | 67 |

Issue number | 7 |

DOIs | |

Publication status | Published - 1998 |

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_{c}superconductors.

*JETP Letters*,

*67*(7), 495-500. https://doi.org/10.1134/1.567716