Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Journal of Physics Condensed Matter

Exact ground states of correlated electronic models: heavy-fermion/bilayer systems

R Sato

Published Mar 17, 1997• 0 citations
Publisher

Abstract

We construct the exact ground states of a class of models for correlated electronic systems in d dimensions. We introduce generalized models for heavy-fermion systems and those for bilayer systems. By the optimal ground state approach, we show that the models have superconducting ground states via the -pairing mechanism. We also obtain the criteria for the stability of charge-density-wave states.

DOI
10.1088/0953-8984/9/11/015

Related papers

Exact Ground States of Generalized Hubbard Models

Jan De Boer A, Andreas Schadschneider

We present a simple method for the construction of exact ground states of generalized Hubbard models in arbitrary dimensions. This method is used to derive rigorous criteria for the stability of various ground state types, like the $\ensuremath{\eta}$-pairing state, or N\'eel and ferromagnetic states. Although the approach presented here is much simpler than the ones commonly used, it yields better bounds for the region of stability.

arXiv:cond-mat/9503122•Physical Review Letters•Dec 4, 1995•76 citations

New exactly solvable model of strongly correlated electrons motivated by high- T c superconductivity

Fabian H. L. Eßler, V. E. Korepin, Kareljan Schoutens

We present a new model describing strongly correlated electrons on a general d-dimensional lattice. It is an extended Hubbard model and it contains the t-J model as a special case. The model naturally describes local electron pairs, which can move coherently at arbitrary momentum. By using an \ensuremath{\eta}-pairing mechanism we can construct eigenstates of the Hamiltonian with off-diagonal long-range order. In the attractive case the exact ground state is superconducting in any number of dimensions. On a one-dimensional lattice, the model is exactly solvable by Bethe ansatz.

arXiv:cond-mat/9209002•Physical Review Letters•May 11, 1992•265 citations

Exact Electron-Pairing Ground States of Tight-Binding Models with Local Attractive Interactions

Akinori Tanaka

We present a class of exactly solvable models of correlated electrons. The models are defined in any dimension $d$ and consist of electron-hopping terms and local attractive interactions between electrons. For each even number of electrons less than or equal to $1/(d+1)$-filling, we find the exact ground state in which all electrons form pairs of a certain type, and thus the models exhibit an electron-pair condensation.

arXiv:cond-mat/0310615•Journal of the Physical Society of Japan•May 15, 2004•2 citations

η -pairing in correlated fermion models with spin-orbit coupling

Li Kai

The authors study the $\ensuremath{\eta}$-pairing phenomenon in correlated fermion models with spin-orbit coupling. Spin-orbit coupled systems are usually thought to possess no continuous symmetries, except the conventional U(1) particle-number symmetry. The $\ensuremath{\eta}$-pairing reveals an exact SU(2) pseudospin symmetry in a broad class of spin-orbit coupled Hubbard models. Furthermore, the authors construct an exactly solvable interacting Dirac-semimetal model that exhibits an exact pseudospin symmetry with fine-tuned parameters. This model hosts $\ensuremath{\eta}$-pairing and charge density wave ground states, which meet at an exactly solvable multicritical line.

arXiv:1901.06914•Physical review. B./Physical review. B•Oct 28, 2020•12 citations

Rigorous results on superconducting ground states for attractive extended Hubbard models

Arianna Montorsi, David K Campbell

We show that the exact ground state for a class of extended Hubbard models including bond-charge, exchange, and pair-hopping terms, is the Yang ``\ensuremath{\eta}-paired'' state for any nonvanishing positive value of the pair-hopping amplitude, at least when the on-site Coulomb interaction is attractive enough and the remaining physical parameters satisfy a single constraint. The ground state is thus rigorously superconducting. Our result holds on a bipartite lattice in any dimension, at any band filling, and for arbitrary electron hopping. \textcopyright{} 1996 The American Physical Society.

arXiv:cond-mat/9502027•Physical review. B, Condensed matter•Mar 1, 1996•36 citations

Correlated-Electron Systems and High-Temperature Superconductivity

Takashi Yanagisawa, Mitake Miyazaki, Yamaji K.

We present recent theoretical results on superconductivity in correlated-electron systems, especially in the two-dimensional Hubbard model and the three-band d-p model. The mechanism of superconductivity in high-temperature superconductors has been extensively studied on the basis of various electronic models and also electron-phonon models. In this study, we investigate the properties of superconductivity in correlated-electron systems by using numerical methods such as the variational Monte Carlo method and the quantum Monte Carlomethod. The Hubbard model is one of basic models for strongly correlated electron systems, and is regarded as the model of cuprate high temperature superconductors. The d-p model is more realistic model for cuprates. The superconducting condensation energy obtained by adopting the Gutzwiller ansatz is in reasonable agreement with the condensation energy estimated for YBa2Cu3O7. We show the phase diagram of the ground state using this method. We have further investigated the stability of striped and checkerboard states in the under-doped region. Holes doped in a half-filled square lattice lead to an incommensurate spin and charge density wave. The relationship of the hole density x and incommensurability δ, δ~x, is satisfied in the lower doping region, as indicated by the variationalMonte Carlocalculations for the two-dimensional Hubbard model. A checkerboard-like charge-density modulation with a roughly period has also been observed by scanning tunneling microscopy experiments in Bi2212 and Na-CCOC compounds. We have performed a variational Monte Carlo simulation on a two-dimensional t-t′-t″- U Hubbard model with a Bi-2212 type band structure and found that the period checkerboard spin modulation, that is characterized by multi Q vectors, is indeed stabilized. We have further performed an investigation by using a quantumMonte Carlomethod, which is a numerical method that can be used to simulate the behavior of correlated electron systems. We present a new algorithm of the quantum Monte Carlo diagonalization that is a method for the evaluation of expectation value without the negative sign problem. We compute pair correlation functions and show that pair correlation is indeed enhanced with hole doping.

arXiv:1307.2456•Journal of Modern Physics•Jan 1, 2013•23 citations
We construct the exact ground states of a class of models for correlated electronic systems in d dimensions. We introduce generalized models for heavy-fermion systems and those for bilayer systems. By the optimal ground state approach, we show that the models have superconducting ground states via the -pairing mechanism. We also obtain the criteria for the stability of charge-density-wave states.
We present a new model describing strongly correlated electrons on a general d-dimensional lattice. It is an extended Hubbard model and it contains the t-J model as a special case. The model naturally describes local electron pairs, which can move coherently at arbitrary momentum. By using an \ensuremath{\eta}-pairing mechanism we can construct eigenstates of the Hamiltonian with off-diagonal long-range order. In the attractive case the exact ground state is superconducting in any number of dimensions. On a one-dimensional lattice, the model is exactly solvable by Bethe ansatz.
We present a class of exactly solvable models of correlated electrons. The models are defined in any dimension ddd and consist of electron-hopping terms and local attractive interactions between electrons. For each even number of electrons less than or equal to 1/(d+1)1/(d+1)1/(d+1)-filling, we find the exact ground state in which all electrons form pairs of a certain type, and thus the models exhibit an electron-pair condensation.
The authors study the $\ensuremath{\eta}$-pairing phenomenon in correlated fermion models with spin-orbit coupling. Spin-orbit coupled systems are usually thought to possess no continuous symmetries, except the conventional U(1) particle-number symmetry. The $\ensuremath{\eta}$-pairing reveals an exact SU(2) pseudospin symmetry in a broad class of spin-orbit coupled Hubbard models. Furthermore, the authors construct an exactly solvable interacting Dirac-semimetal model that exhibits an exact pseudospin symmetry with fine-tuned parameters. This model hosts $\ensuremath{\eta}$-pairing and charge density wave ground states, which meet at an exactly solvable multicritical line.
We show that the exact ground state for a class of extended Hubbard models including bond-charge, exchange, and pair-hopping terms, is the Yang ``\ensuremath{\eta}-paired'' state for any nonvanishing positive value of the pair-hopping amplitude, at least when the on-site Coulomb interaction is attractive enough and the remaining physical parameters satisfy a single constraint. The ground state is thus rigorously superconducting. Our result holds on a bipartite lattice in any dimension, at any band filling, and for arbitrary electron hopping. \textcopyright{} 1996 The American Physical Society.
We present recent theoretical results on superconductivity in correlated-electron systems, especially in the two-dimensional Hubbard model and the three-band d-p model. The mechanism of superconductivity in high-temperature superconductors has been extensively studied on the basis of various electronic models and also electron-phonon models. In this study, we investigate the properties of superconductivity in correlated-electron systems by using numerical methods such as the variational Monte Carlo method and the quantum Monte Carlomethod. The Hubbard model is one of basic models for strongly correlated electron systems, and is regarded as the model of cuprate high temperature superconductors. The d-p model is more realistic model for cuprates. The superconducting condensation energy obtained by adopting the Gutzwiller ansatz is in reasonable agreement with the condensation energy estimated for YBa2Cu3O7. We show the phase diagram of the ground state using this method. We have further investigated the stability of striped and checkerboard states in the under-doped region. Holes doped in a half-filled square lattice lead to an incommensurate spin and charge density wave. The relationship of the hole density x and incommensurability δ, δ~x, is satisfied in the lower doping region, as indicated by the variationalMonte Carlocalculations for the two-dimensional Hubbard model. A checkerboard-like charge-density modulation with a roughly period has also been observed by scanning tunneling microscopy experiments in Bi2212 and Na-CCOC compounds. We have performed a variational Monte Carlo simulation on a two-dimensional t-t′-t″- U Hubbard model with a Bi-2212 type band structure and found that the period checkerboard spin modulation, that is characterized by multi Q vectors, is indeed stabilized. We have further performed an investigation by using a quantumMonte Carlomethod, which is a numerical method that can be used to simulate the behavior of correlated electron systems. We present a new algorithm of the quantum Monte Carlo diagonalization that is a method for the evaluation of expectation value without the negative sign problem. We compute pair correlation functions and show that pair correlation is indeed enhanced with hole doping.