<i><i>d</i></i>-Wave State with Multiplicative Correlation Factors for the Hubbard Model

Yanagisawa, Takashi; Koike, Soh; Yamaji, Kunihiko

doi:10.1143/jpsj.68.3608

Cited by 30 publications

(40 citation statements)

References 24 publications

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“…54 This agreement between the theoretical and experimental condensation energy is highly remarkable. We expect that this value is not far from the correct value according to the evaluations for improved wave functions, 51 where it was shown that the energy gain is not changed so much due to multiplicative correlation factors e −∆τ H0 e −∆τ V . We cannot estimate the SC condensation energy in the underdoped region because the SDW state is more stable than d-wave state and the SC condensation energy is not available experimentally due to a loss of entropy in the underdoped region.…”

Section: Condensation Energy and Phase Diagrammentioning

confidence: 88%

Ground state of the three-band Hubbard model

2001

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The ground state of the two-dimensional three-band Hubbard model in the oxide superconductors is investigated by using the variational Monte Carlo method. The Gutzwiller-projected BCS and SDW wave functions are employed in search for a possible ground state with respect to dependences on electron density. Antiferromagnetic correlations are considerably strong near half-filling. It is shown that the d-wave state may exist away from half-filling for both the hole and electron doping cases. Overall structure of the phase diagram obtained by our calculations qualitatively agrees with experimental indications. The superconducting condensation energy is in reasonable agreement with the experimental value obtained from specific heat and critical magnetic field measurements for optimally doped samples. The inhomogeneous SDW state is also examined near 1/8 doping. Incommensurate magnetic structures become stable due to hole doping in the underdoped region, where the transfer tpp between oxygen orbitals plays an important role in determining a stable stripe structure.

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Section: Condensation Energy and Phase Diagrammentioning

confidence: 88%

Ground state of the three-band Hubbard model

2001

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“…We uset d p = t d p as the energy unit. We consider the following wave function that is improved from the Gutzwiller wave function: 50,73,[186][187][188][189][190]…”

Section: Optimization Variational Monte Carlo Methods 321 Off-diagonmentioning

confidence: 99%

Mechanism of High-Temperature Superconductivity in Correlated-Electron Systems

Yanagisawa¹

2019

Condensed Matter

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It is very important to elucidate the mechanism of superconductivity for achieving room temperature superconductivity. This paper is a short review article on the mechanism of high-temperature superconductivity. In the first half of this paper, we give a brief review on mechanisms of superconductivity in many-electron systems. We believe that hightemperature superconductivity may occur in a system with interaction of large-energy scale. Empirically, this is true for superconductors that have been found so far. In the second half of this paper, we discuss cuprate high-temperature superconductors. We argue that superconductivity of high temperature cuprates is induced by the strong on-site Coulomb interaction, that is, the origin of high-temperature superconductivity is the strong electron correlation. We show the results on the ground state of electronic models for high temperature cuprates on the basis of the optimization variational Monte Carlo method. A high-temperature superconducting phase will exist in the strongly correlated region.

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“…For the wave functions ψ (2) , ψ (3) ,· · · , it is difficult to impose the sitediagonal-type constraint P Ne to fix the total electron number. To introduce the off-diagonal long-range order in the wave function with off-diagonal site correlation, we perform the electron-hole transformation for down-spin electrons [54]:…”

Section: B Improved Wave Functionsmentioning

confidence: 99%

Crossover from Weakly to Strongly Correlated Regions in the Two-dimensional Hubbard Model — Off-diagonal Wave Function Monte Carlo Studies of Hubbard Model II —

Yanagisawa

2016

J. Phys. Soc. Jpn.

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The ground state of the two-dimensional (2D) Hubbard model is investigated by adopting improved wave functions that take into account intersite electron correlation beyond the Gutzwiller ansatz. The ground-state energy is lowered considerably, giving the best estimate of the groundstate energy for the 2D Hubbard model. There is a crossover from weakly to strongly correlated regions as the on-site Coulomb interaction U increases. The antiferromagnetic correlation induced by U is reduced for hole doping when U is large, being greater than the bandwidth, thus increasing the kinetic energy gain. The spin and charge fluctuations are induced in the strongly correlated region. These antiferromagnetic and kinetic charge fluctuations induce electron pairings, which result in high-temperature superconductivity.

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d-Wave State with Multiplicative Correlation Factors for the Hubbard Model

Cited by 30 publications

References 24 publications

Ground state of the three-band Hubbard model

Ground state of the three-band Hubbard model

Mechanism of High-Temperature Superconductivity in Correlated-Electron Systems

Crossover from Weakly to Strongly Correlated Regions in the Two-dimensional Hubbard Model — Off-diagonal Wave Function Monte Carlo Studies of Hubbard Model II —

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