From known phase diagram regions of different model Hamiltonians describing strongly correlated systems we deduced new domains of the ground state phase diagram of the same models by a unitary transformation. Different types of extended Hubbard Hamiltonians were used for the starting point and the existence of new stable spin-density waves, charge-density waves, ferromagnetic states and a paramagnetic insulator is demonstrated. The procedure used is dimension independent. The ground state phase diagrams of several strongly correlated systems modelled by extended Hubbard-like Hamiltonians are analysed using unitary transformations. New stable spin-density wave, charge-density wave, ferromagnetic or paramagnetic insulator phases are obtained in different cases. The results are true in any dimensions. SUMMARY In this paper, we have presented a procedure based on an explicitly given unitary transformation which allows the rigorous deduction of new phase diagram domains starting from known ground state solutions of a given model. The method is not model dependent and can be applied for arbitrary dimensions. We have applied this method to find new stable spin-density wave, charge-density wave, ferromagnetic and paramagnetic insulator domains of different extended Hubbard type models.From known phase diagram regions of different model Hamiltonians describing strongly correlated systems we deduced new domains of the ground state phase diagram of the same models by a unitary transformation. Different types of extended Hubbard Hamiltonians were used for the starting point and the existence of new stable spin-density waves, charge-density waves, ferromagnetic states and a paramagnetic insulator is demonstrated. The procedure used is dimension independent. The ground state phase diagrams of several strongly correlated systems modelled by extended Hubbard-like Hamiltonians are analysed using unitary transformations. New stable spin-density wave, charge-density wave, ferromagnetic or paramagnetic insulator phases are obtained in different cases. The results are true in any dimensions. SUMMARY In this paper, we have presented a procedure based on an explicitly given unitary transformation which allows the rigorous deduction of new phase diagram domains starting from known ground state solutions of a given model. The method is not model dependent and can be applied for arbitrary dimensions. We have applied this method to find new stable spin-density wave, charge-density wave, ferromagnetic and paramagnetic insulator domains of different extended Hubbard type models.

arXiv:cond-mat/0104143Philosophical Magazine BMar 1, 20013 citations

Paramagnetism and superconductivity in the Hubbard model with strong repulsion

R. O. Zaǐtsev

Physica C SuperconductivityDec 1, 19940 citations

Quantum Paramagnet in a π Flux Triangular Lattice Hubbard Model

Stephan Rachel, Manuel Laubach, Johannes Reuther +1 more

We propose the $\ensuremath{\pi}$ flux triangular lattice Hubbard model ($\ensuremath{\pi}$ THM) as a prototypical setup to stabilize magnetically disordered quantum states of matter in the presence of charge fluctuations. The quantum paramagnetic domain of the $\ensuremath{\pi}$ THM that we identify for intermediate Hubbard $U$ is framed by a Dirac semimetal for weak coupling and by 120\ifmmode^\circ\else\textdegree\fi{} N\'eel order for strong coupling. Generalizing the Klein duality from spin Hamiltonians to tight-binding models, the $\ensuremath{\pi}$ THM maps to a Hubbard model which corresponds to the $({J}_{\mathrm{H}},{J}_{\mathrm{K}})=(\ensuremath{-}1,2)$ Heisenberg-Kitaev model in its strong coupling limit. The $\ensuremath{\pi}$ THM provides a promising microscopic testing ground for exotic finite- $U$ spin liquid ground states amenable to numerical investigation.We propose the $\ensuremath{\pi}$ flux triangular lattice Hubbard model ($\ensuremath{\pi}$ THM) as a prototypical setup to stabilize magnetically disordered quantum states of matter in the presence of charge fluctuations. The quantum paramagnetic domain of the $\ensuremath{\pi}$ THM that we identify for intermediate Hubbard $U$ is framed by a Dirac semimetal for weak coupling and by 120\ifmmode^\circ\else\textdegree\fi{} N\'eel order for strong coupling. Generalizing the Klein duality from spin Hamiltonians to tight-binding models, the $\ensuremath{\pi}$ THM maps to a Hubbard model which corresponds to the $({J}_{\mathrm{H}},{J}_{\mathrm{K}})=(\ensuremath{-}1,2)$ Heisenberg-Kitaev model in its strong coupling limit. The $\ensuremath{\pi}$ THM provides a promising microscopic testing ground for exotic finite-$U$ spin liquid ground states amenable to numerical investigation.

arXiv:1411.4649Physical Review LettersApr 23, 201520 citations

The Hubbard Hamiltonian and its symmetries

Fabian H. L. Eßler, Holger Frahm, Frank Göhmann +2 more

Cambridge University Press eBooksFeb 7, 20052 citations

U

is framed by a Dirac semimetal for weak coupling and by 120\ifmmode^\circ\else\textdegree\fi{} N\'eel order for strong coupling. Generalizing the Klein duality from spin Hamiltonians to tight-binding models, the $\ensuremath{\pi}$ THM maps to a Hubbard model which corresponds to the $({J}_{\mathrm{H}},{J}_{\mathrm{K}})=(\ensuremath{-}1,2)$ Heisenberg-Kitaev model in its strong coupling limit. The $\ensuremath{\pi}$ THM provides a promising microscopic testing ground for exotic finite-

U

spin liquid ground states amenable to numerical investigation.