Charge instabilities and topological phases in the extended Hubbard model on the honeycomb lattice with enlarged unit cell

Abstract

We study spontaneous symmetry breaking in a system of spinless fermions in the honeycomb lattice paying special emphasis to the role of an enlarged unit cell on time reversal symmetry broken phases. We use a tight-binding model with nearest-neighbor hopping t and Hubbard interaction V 1 and V 2 and extract the phase diagram as a function of electron density and interaction within a mean-field variational approach. The analysis completes the previous work done in Phys. Rev. Lett. 107, 106402 (2011) where phases with nontrivial topological properties were found with only a nearest-neighbor interaction V 1 in the absence of charge decouplings. We see that the topological phases are suppressed by the presence of metallic charge density fluctuations. The addition of next to nearest-neighbor interaction V 2 restores the topological nontrivial phases.

Competition of density waves and quantum multicritical behavior in Dirac materials from functional renormalization

“…Dirac materials [1], such as graphene [2][3][4] and a growing number of novel two-dimensional systems, exhibit a huge variety of possible ordered states in the presence of sufficiently strong interactions [5][6][7][8][9][10][11][12][13][14][15][16]. By inreasing, for instance, repulsive onsite or nearest-neighbor densitydensity interactions, these systems are expected to exhibit a continuous quantum phase transition from the semimetallic phase into spin-density-wave (SDW) and charge-density-wave (CDW) phases, respectively [16][17][18][19].…”

Effective field theory of an anomalous Hall metal from interband quantum fluctuations

“…Moreover in Ref. 66, an extended Hubbard model of spinless electrons on the honeycomb lattice was shown to have metallic anomalous Hall phases and (C 6 breaking) Pomenranchuk phases within the mean-field approximation.…”

Роль Электрон-Электронного Отталкивания В Задаче Об Эпитаксиальном Графене На Металле: Простые Оценки

“…Инте-ресно отметить, что значение U = 3.5t является кри-терием, разделяющим бесщелевую квантовую спиновую жидкость и квантовую спиновую жидкость, обладающую щелью [3,25]. Справедливости ради следует упомянуть и работы [5,[26][27][28], где оценки соотношения между U и t отличаются от приведенных выше. 4.3.…”

“…Следует отметить также, что в большинстве работ по данной тематике рассматривается недопированный случай. Как, однако, показано в [27,28], допирование может приводить к новым фазовым состо-яниям двумерной гексагональной структуры.…”