Quantum Phase Transitions in the Hubbard Model on a Triangular Lattice

We investigate the quantum phase transitions in the half-filled Hubbard model on the triangular lattice by means of the path-integral renormalization group (PIRG) method with a new iteration scheme proposed recently. It is found that as the Hubbard interaction $U$ increases, the paramagnetic metallic state undergoes a first-order phase transition to a nonmagnetic insulating (NMI) state at $U_{c1}\sim 7.7t$ , which is followed by another first-order transition to a $120^\circ$ Néel ordered state at $U_{c2}\sim 10t$ , where $t$ is the transfer integral. Our results ensure the existence of the intermediate NMI phase, and resolve some controversial arguments on the nature of the previously proposed quantum phase transitions. We find that $κ$ -(BEDT-TTF) $_2$ Cu $_2$ (CN) $_3$ is located in the NMI phase close to the metal-insulator transition point.We investigate the quantum phase transitions in the half-filled Hubbard model on the triangular lattice by means of the path-integral renormalization group (PIRG) method with a new iteration scheme proposed recently. It is found that as the Hubbard interaction $U$ increases, the paramagnetic metallic state undergoes a first-order phase transition to a nonmagnetic insulating (NMI) state at $U_{c1}\sim 7.7t$, which is followed by another first-order transition to a $120^\circ$ Néel ordered state at $U_{c2}\sim 10t$, where $t$ is the transfer integral. Our results ensure the existence of the intermediate NMI phase, and resolve some controversial arguments on the nature of the previously proposed quantum phase transitions. We find that $κ$-(BEDT-TTF)$_2$Cu$_2$(CN)$_3$ is located in the NMI phase close to the metal-insulator transition point.

arXiv:0811.1575Nov 10, 20081 citation

Quantum Phase transitions in Hubbard lattices

Matteo Rizzi, Rosario Fazio

Jan 1, 20071 citation

Quantum phase transition of the Hubbard model on a honeycomb lattice

Ara Go, Kwon Park, Gun Sang Jeon

Bulletin of the American Physical SocietyMar 19, 20100 citations

U

increases, the paramagnetic metallic state undergoes a first-order phase transition to a nonmagnetic insulating (NMI) state at

U_{c1}\sim 7.7t

, which is followed by another first-order transition to a

120^\circ

Néel ordered state at

U_{c2}\sim 10t

, where

t

is the transfer integral. Our results ensure the existence of the intermediate NMI phase, and resolve some controversial arguments on the nature of the previously proposed quantum phase transitions. We find that

κ

-(BEDT-TTF)

_2

_2

(CN)

_3

is located in the NMI phase close to the metal-insulator transition point.