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Volumn 75, Issue 7, 2006, Pages

Superconductivity and a Mott transition in a Hubbard model on an anisotropic triangular lattice

Author keywords

(BEDT TTF)2X; Anisotropic triangular lattice; Antiferromagnetic correlation; Dx2 y2 wave; Hubbard model; Mott transition; Superconductivity; Variational Monte Carlo method

Indexed keywords


EID: 33847377227     PISSN: 00319015     EISSN: 13474073     Source Type: Journal    
DOI: 10.1143/JPSJ.75.074707     Document Type: Article
Times cited : (106)

References (90)
  • 1
    • 0031200418 scopus 로고    scopus 로고
    • K. Kanoda: Physica C 282-287 (1997) 299;
    • (1997) Physica C , vol.282-287 , pp. 299
    • Kanoda, K.1
  • 17
    • 33847394875 scopus 로고    scopus 로고
    • In this paper, we use the term Mott transition for a transition from a conductive state to a nonmagnetic insulating state. Thus, we discriminate it from a magnetic transition like a metal-to-AF-insulator transition
    • In this paper, we use the term "Mott transition" for a transition from a conductive state to a nonmagnetic insulating state. Thus, we discriminate it from a magnetic transition like a metal-to-AF-insulator transition.
  • 28
    • 33847380565 scopus 로고    scopus 로고
    • At half filling, the results for t′ (< 0) are identical to those for |t′, We hence concentrate on the case of t′/t ≥ 0
    • At half filling, the results for t′ (< 0) are identical to those for |t′|. We hence concentrate on the case of t′/t ≥ 0.
  • 36
    • 33847401380 scopus 로고    scopus 로고
    • Because the t-J and Hubbard models are related in the strong coupling regime through a canonical transformation, ℋt-J ≈ eiSℋHube-iS,36 in which S is given as Σ〈ij〉σ -it/U [ni-σ(1-n j-σ)ciσ† cjσ(1-ni-σ) ciσ†cjσ] the expectation values of the t-J model with respect to ΨG are approximately equivalent to those of the Hubbard model with respect to e-iSΨG. When one expands e -iS, the first-order part (∼t/U) of e -iSΨG broadly corresponds to ℘QΨG. Thus, the favorable fe
    • QΨG.
  • 43
    • 33847391527 scopus 로고    scopus 로고
    • It is difficult to estimate proper values of Z as a function of U/t with a finite-sized system, in the case that the position of the quasi-Fermi point moves and crosses a k point, when U/t is varied. As an example, we show the case of t′/t = 0.4 and L = 12 in Fig. 6, where the data for U/t = 6.5 deviates to some extent. For this parameter set, we find the quasi-Fermi point to shift in the nodal direction in Fig. 5(a).
    • It is difficult to estimate proper values of Z as a function of U/t with a finite-sized system, in the case that the position of the quasi-Fermi point moves and crosses a k point, when U/t is varied. As an example, we show the case of t′/t = 0.4 and L = 12 in Fig. 6, where the data for U/t = 6.5 deviates to some extent. For this parameter set, we find the quasi-Fermi point to shift in the nodal direction in Fig. 5(a).
  • 46
    • 33847381026 scopus 로고    scopus 로고
    • Generally, as system size decreases, the critical behavior near a phase transition tends to be less sharp, because a transition, in a strict sense, takes place only for Ns → ∞. For instance, the curve for t′, 0 and L, 10 in Fig. 8 (open square) is relatively smooth, whereas the curve for L, 16 seems to have an obvious jump. Thus, one must necessarily check system-size dependence to treat a phase transition
    • s → ∞. For instance, the curve for t′ = 0 and L = 10 in Fig. 8 (open square) is relatively smooth, whereas the curve for L = 16 seems to have an obvious jump. Thus, one must necessarily check system-size dependence to treat a phase transition.
  • 57
    • 33644940381 scopus 로고    scopus 로고
    • For instance
    • For instance, M. Imada: Phys. Rev. B 72 (2005) 075113.
    • (2005) Phys. Rev. B , vol.72 , pp. 075113
    • Imada, M.1
  • 58
    • 33847359077 scopus 로고    scopus 로고
    • We adopt the Manhattan metric to measure |R| and |r|.
    • We adopt the Manhattan metric to measure |R| and |r|.
  • 59
    • 33847386210 scopus 로고    scopus 로고
    • d(r) in eq. (17) is useful, because we are interested in the SC arising, particularly, near the Mott transition.
    • d(r) in eq. (17) is useful, because we are interested in the SC arising, particularly, near the Mott transition.
  • 60
    • 33847391964 scopus 로고    scopus 로고
    • c for t′/t = 0.7 and 0.8.
    • c for t′/t = 0.7 and 0.8.
  • 65
    • 0031327963 scopus 로고    scopus 로고
    • This feature is similar to that in the inorganic spin-Peierls compound CuGeO3, in which the value of J′/J drastically varies (including sign) under pressure. See, e.g, H. Yokoyama and Y. Saiga: J. Phys. Soc. Jpn. 66 (1997) 3617;
    • 3, in which the value of J′/J drastically varies (including sign) under pressure. See, e.g., H. Yokoyama and Y. Saiga: J. Phys. Soc. Jpn. 66 (1997) 3617;
  • 89
    • 33847387050 scopus 로고    scopus 로고
    • The effect of difference (i, namely of t″/t, must be slight, because, according to Fig. 2 in ref. 23, the optimized |t″/t| is small both for the conductive (U/t ≲ 8.5) and insulating (U/t ≲ 8.5) phases. The effect of difference (ii, namely of putting μ′, μ in ΨLiu, manifests itself to some extent, because, as in Figs. 4(d) and 4e, the optimized values of μ and μ′ are quite different, especially in the insulating phase. Thus, it is possible that ΨLiu becomes quantitatively worse than ΨdQ for U ≲ Uc; better results would be obtained, if μ′, 0 is used instead of μ′, μ in ΨLiu
    • Liu.
  • 90
    • 33847394451 scopus 로고    scopus 로고
    • In ref. 23, the system-size dependence of the gap parameter Δ0/t* for U/t, 9.5 (in the insulating regime) is shown in the inset of Fig. 1. Because the finite Δ0/ t* does not necessarily indicate the realization of SC, as we have mentioned, it is useless to check whether Δ0/t* remains finite for L → ∞, in order to determine whether or not SC arises
    • 0/t* remains finite for L → ∞, in order to determine whether or not SC arises.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.