Mott Transitions and <i>d</i>-Wave Superconductivity in Half-Filled-Band Hubbard Model on Square Lattice with Geometric Frustration

Yokoyama, Hisayuki; Ogata, Masao; Tanaka, Yukio

doi:10.1143/jpsj.75.114706

Cited by 133 publications

(171 citation statements)

References 56 publications

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“…Hubbard models have been extensively studied, and we have shown that a first-order Mott transition occurs at U = U c ∼ W at half filling for nonmagnetic near half filling. [33][34][35] In this paper, we show that similar Mott physics appears in the SF states. It has been shown that, in a wide range of the parameter space of concern, a d-SC state becomes stable compared with the projected Fermi sea (ordinary normal state).…”

Section: Hubbard Modelsupporting

confidence: 63%

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Staggered Flux State in Two-Dimensional Hubbard Models

2016

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The stability and other properties of a staggered flux (SF) state or a correlated d-density wave state are studied for the Hubbard (t-t ′ -U) model on extended square lattices, as a low-lying state that competes with the d x 2 −y 2 -wave superconductivity (d-SC) and possibly causes the pseudogap phenomena in underdoped high-T c cuprates and organic κ-BEDT-TTF salts. In calculations, a variational Monte Carlo method is used. In the trial wave function, a configurationdependent phase factor, which is vital to treat a current-carrying state for a large U/t, is introduced in addition to ordinary correlation factors. Varying U/t, t ′ /t, and the doping rate (δ) systematically, we show that the SF state becomes more stable than the normal state (projected Fermi sea) for a strongly correlated (U/t 5) and underdoped (δ 0.16) area. The decrease in energy is sizable, particularly in the area where Mott physics prevails and the circular current (order parameter) is strongly suppressed. These features are consistent with those for the t-J model. The effect of the frustration t ′ /t plays a crucial role in preserving charge homogeneity and appropriately describing the behavior of holeand electron-doped cuprates and κ-BEDT-TTF salts. We argue that the SF state does not coexist with d-SC and is not a 'normal state' from which d-SC arises. We also show that a spin current (flux or nematic) state is never stabilized in the same regime.

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Section: Hubbard Modelsupporting

confidence: 63%

“…However, because the behavior of both ζ and d becomes more singular as L increases, we consider that this transition is first-order, similarly to those in Ψ d and Ψ N . 34 …”

Section: Variational Energymentioning

confidence: 99%

Staggered Flux State in Two-Dimensional Hubbard Models

2016

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“…As mentioned above, this behavior of |z N | indicates that the system is conductive (insulating) for U/t < 6.5 (U/t > 6.5), and at U/t = 6.5 a sharp (first-order-like) SC-insulator transition arises. This result is quantitatively consistent with that of the previous studies [6,15,16], in which this Mott transition was confirmed by various quantities such as a SC pairing correlation function and the Drude weight. The behavior of |z N | of Ψ N is similar to that of Ψ SC except for the Mott transition point, and is consistent with that of the previous results.…”

Section: Resultssupporting

confidence: 93%

Variational Approach to Localization Length for Two-Dimensional Hubbard Model

Tamura

Yokoyama²

2014

Proceedings of the International Conference on Strongly Correlated Electron Systems (SCES2013)

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As a measure to ascertain whether a system is metallic or insulating, localization length λ N , which represents the spread of electron distribution, can be a useful quantity, especially for approaching a metal-insulator transition from the insulator side. We try to calculate λ N using a variational Monte Carlo method for normal (paramagnetic), superconducting and antiferromagnetic states in the squarelattice Hubbard model. It is found that the behavior of λ N is consistent with what is expected from other quantities, and gives information complementary to another measure, the Drude weight.

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“…In principle, the Gutzwiller-type variational wave function gives the Mott transition as a function of U , when charge fluctuations, which play an important role in the vicinity of the Mott transition, 36 are included. [37][38][39][40][41] However, the present study using the GA is inappropriate to address the possibility of the Mott transition. Thus, we have shown the results only for the case with U/W tot ≤ 1.4 where the system will remain metallic.…”

Section: B Gutzwiller Approximationmentioning

confidence: 99%

Origin of the heavy fermion behavior in Ca2−xSrxRuO4
Arakawa
¹
,
Ogata
²

2012
Phys. Rev. B
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We study the electronic states for Ca2−xSrxRuO4 in 0.5 ≤ x ≤ 2 within the Gutzwiller approximation (GA) on the basis of the three-orbital Hubbard model for the Ru t2g orbitals. The main effects of the Ca-substitution are taken into account as the changes of the dp hybridizations between the Ru 4d and O 2p orbitals. Using the numerical minimization of the energy obtained in the GA, we obtain the renormalization factor (RF) of the kinetic energy and total RF, which estimates the inverse of the mass enhancement, for three cases with the effective models of x = 2 and 0.5 and a special model. We find that the inverse of the total RF becomes the largest for the case of x = 0.5, and that the van Hove singularity, which is located on (below) the Fermi level for the special model (the effective model of x = 0.5), plays a secondary role in enhancing the effective mass. Our calculation suggests that the heavy fermion behavior around x = 0.5 comes from the cooperative effects between moderately strong Coulomb interaction compared to the total bandwidth and the modification of the electronic structures due to the rotation of RuO6 octahedra (i.e., the variation of the dpπ hybridizations and the downward shift for the dxy orbital). We propose that moderately strong electron correlation and the orbital-dependent modifications of the electronic structures due to the lattice distortions play important roles in the electronic states for Ca2−xSrxRuO4.

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Mott Transitions and d-Wave Superconductivity in Half-Filled-Band Hubbard Model on Square Lattice with Geometric Frustration

Cited by 133 publications

References 56 publications

Staggered Flux State in Two-Dimensional Hubbard Models

Staggered Flux State in Two-Dimensional Hubbard Models

Variational Approach to Localization Length for Two-Dimensional Hubbard Model

Origin of the heavy fermion behavior in Ca2−xSrxRuO4
Arakawa
¹
,
Ogata
²

2012
Phys. Rev. B
Self Cite
8
1
22
0
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Mott Transitions and d-Wave Superconductivity in Half-Filled-Band Hubbard Model on Square Lattice with Geometric Frustration

Cited by 133 publications

References 56 publications

Staggered Flux State in Two-Dimensional Hubbard Models

Staggered Flux State in Two-Dimensional Hubbard Models

Variational Approach to Localization Length for Two-Dimensional Hubbard Model

Origin of the heavy fermion behavior in Ca2−xSrxRuO4Arakawa1, Ogata2 2012Phys. Rev. BSelf Cite81220View full textAdd to dashboardCite

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Origin of the heavy fermion behavior in Ca2−xSrxRuO4
Arakawa
¹
,
Ogata
²

2012
Phys. Rev. B
Self Cite
8
1
22
0
View full text Add to dashboard Cite