セミナー情報

原子力機構・兵県大合同物性コロキウム(第64回)

日時: 平成22年2月4日(木) 16:00〜
Date and time: 4th February (Thu.) 16:00〜
場所: SPring-8, 萌光館
Place: SPring-8, "HOUKOUKAN" seminar room
Title: Numerical study of quarter-filled extended Hubbard model coupled to Ising chain in 1D
講演者: 大塚雄一  氏 (理研、JST-CREST)
Speaker: Dr. Yuichi Otsuka (Riken, JST-CREST)
Abstract:

π-d systems, in which itinerant π-electrons are coupled to localized d-electrons, have recently attracted much interest in the field of the molecular conductors. Among them, the one-dimensional (1D) conductor TPP[Fe(Pc)(CN)2]2 has been intensively studied [1], which is found to show giant negative magnetoresistance (MR) [2] owing to the coupling between the π-electrons on Pc and Fe d-spins. In order to understand the origin of such intriguing properties, we have performed Monte Carlo simulations on a 1D π-d coupled model, where the quarter-filled extended Hubbard model for the π-electrons and the antiferromagnetic (AF) Ising chain for the d-spins interact via intramolecular ferromagnetic Hund's-rule coupling. We find that the AF correlation among the d-spins, combined with the inter-site Coulomb interaction, considerably enhances the charge-order correlation in the π-electrons through the π-d coupling and induces ferromagnetic correlations, which is consistent with the experimental features. We also discuss effects of magnetic field on this model and compare our results with the MR effect.

[1] T. Inabe, H. Tajima, Chem. Rev. 104 (2004) 5503.
[2] N. Hanasaki et al., Phys. Rev. B 62 (2000) 5839.