Kinetic-energy pairing and condensation energy in cuprates

Masao Ogata, Hisatoshi Yokoyama, Youichi Yanase, Yukio Tanaka, Hiroki Tsuchiura

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

In order to study the condensation energy in cuprates and the possibility of kinetic-energy pairing, we study the two-dimensional Hubbard model on a square lattice near half-filling using a variational Monte Carlo method for superconductivity. We modify the variational wave function by taking account of the nearest-neighbor correlation between holons and doublons. It is found that there is a qualitative difference between the weak-coupling region and the strong-coupling region. In the strong-coupling region (U≳Uco), the energy gain at the superconducting transition is derived from the kinetic-energy, while in the weak-coupling region (U≲Uco), a conventional BCS-type potential-energy gain occurs. Condensation energy is large in the strong-coupling side and expressed as ∝exp(-4at/J) with a being a constant and J=4t2/U. This result with recent experiments of optical conductivity implies that cuprate superconductors belong to the strong-coupling region. Similar but slightly different condensation energy is also obtained in the calculation using the fluctuation exchange (FLEX) approximation.

Original languageEnglish
Pages (from-to)37-40
Number of pages4
JournalJournal of Physics and Chemistry of Solids
Volume67
Issue number1-3
DOIs
Publication statusPublished - 2006 Jan 1

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

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