Continuous Mott transition in a two-dimensional Hubbard model

Abstract

We investigate nonmagnetic metal-insulator transition in the 1/5-depleted square lattice Hubbard model at half-filling within the 8-site cellular dynamical mean field theory. We find that a metalinsulator transition without any signatures of the first order transition, a continuous Mott transition, takes place in a certain range of parameters. The nature of the continuous Mott transition is nothing but a Lifshitz transition driven by the on-site Coulomb interaction. The renormalized matrix elements of hoppings and the spin-spin correlation functions reveal that physics of this transition is strong enhancement of the dimerization due to the non-local effects of electron-electron interaction.

Single-orbital realization of high-temperature s± superconductivity in the square-octagon lattice

“…First-principles calculations indicate that such a planar structure is kinetically stable at low temperature [12,13] and that its energy is a local minimum [12], which suggests that the material can potentially be synthesized in laboratories. Actually, this lattice structure has attracted a lot of research interest recently because it not only is hosted by quite a few real materials [14][15][16][17] but also has various intriguing phases on this lattice that have been revealed by theoretical calculations [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35]. Here we notice another remarkable property of this 2D lattice: its band structure can have perfect Fermisurface (FS) nesting in a wide parameter regime at half filling, which easily leads to antiferromagnetic SDW order.…”

Magnetic phase diagram and Mott transition of the half-filled15-depleted Hubbard model with frustration

“…Comparing with the CDMFT [10], our U M I is smaller than that of CDMFT. This tendency is observed also e.g., on another non-Brave lattice: the kagomé lattice [14,15].…”

“…The magnetic properties are investigated by the determinant quantum Monte Carlo(DQCM) [11], which reports that the dominant magnetism is the (π, π) Néel ordering, but the Mott transition was not analyzed. Moreover, the effect of the next nearest hoppings, which is in general not negligible [7,8] and expected to largely affect the magnetic properties, was not considered in these analyses [10,11]. In this paper we investigate the magnetic phase diagram and Mott transition in the half-filled Hubbard model on the 1/5-depleted square lattice taking into account the effect of the frustration at zero temperature by the variational cluster approximation (VCA).…”

“…1 (b) and (c)) separates two spin gapped states, one adiabatically connected to decoupled dimers, the other connected to decoupled plaquettes, by the second order quantum transition [3][4][5][6][7][8][9]. As for the effect of the electron correlations, the Mott transition was recently studied using the Hubbard model by cluster dynamical meanfield theory(CDMF) [10], but this analysis assumed the non-magnetic ground state and if the Mott transition is veiled or not by the (π, π) Néel ordering is not clear. The magnetic properties are investigated by the determinant quantum Monte Carlo(DQCM) [11], which reports that the dominant magnetism is the (π, π) Néel ordering, but the Mott transition was not analyzed.…”

Theoretical prediction of fragile Mott insulators on plaquette Hubbard lattices

“…The 1/5-depleted square lattice [23][24][25] was first discovered in the study of spin-gapped calcium vanadate material CaV 4 O 9 [23], and later on, in a vacancy-ordered iron selenide family of pnictides [26][27][28] where a rich variety of phases, including several magnetically ordering and superconducting, have been observed [29,30]. Recently, the half-filled Hubbard model on this lattice has been studied with different numerical methods, including CDMFT with continuoustime quantum Monte Carlo impurity solver [31], determinantal quantum Monte simulations [32], and variational cluster approximation [33]. However, a systematic study in which magnetic to non-magnetic phase transition, Mott metal-insulator transition, as well as the realization of a fragile Mott insulator phase, has not been carried out.…”