Many-body effects on graphene conductivity: Quantum Monte Carlo calculations

Abstract

Optical conductivity of graphene is studied using Quantum Monte Carlo calculations. We start from Euclidean current-current correlator and extract σ(ω) from Green-Kubo relations using Backus-Gilbert method. Calculations were performed both for long-range interactions and taking into account only contact term. In both cases we vary interaction strength and study its influence on optical conductivity. We compare our results with previous theoretical calculations choosing ω ≈ κ thus working in the region of the plateau in σ(ω) which corresponds to optical conductivity of Dirac quasiparticles. No dependence of optical conductivity on interaction strength is observed unless we approach antiferromagnetic phase transition in case of artificially enhanced contact term. Our results strongly support previous theoretical studies claimed very weak regularization of graphene conductivity.onto p z subspace results in a noticeable screening of effective interaction potential at intermediate distances in comparison with the bare Coulomb [10] which does not change qualitatively perturbative results [11] but shifts the point of semimetal-insulator transition making freely suspended graphene semimetallic [12].

Topological phase transitions and universality in the Haldane-Hubbard model

“…Our results require the interaction to be weak and short-range; instead, different features are expected in the presence of long-range interactions. For instance, it is known that, at the graphene point, long-range interactions have dramatic effects on several physical properties 23,69 , and their role on the renormalization of the optical conductivity is still actively debated [51][52][53][54][55][56][57][58][59][60] . We expect such effects to have profound implications for the Haldane-Hubbard model, especially in the proximity of the critical lines separating the different topological phases.…”

Monte Carlo study of Dirac semimetals phase diagram

“…To carry out this study we are going to use lattice Monte Carlo simulation, which fully accounts for many-body effects in Dirac semimetals for an arbitrary coupling constant α eff . This approach proved to be very efficient in studying the properties of the strongly correlated systems, for instance, graphene [14][15][16][17][18][19]. We would like to stress that the advantage of our approach compared to the others is that one does not need to make any assumptions about the Dirac model.…”

Field theoretic renormalization study of interaction corrections to the universal ac conductivity of graphene

“…There has therefore been extensive theoretical works during the past decade devoted to understanding the intriguing effect of interactions on the optical conductivity of graphene in the collisionless limit, see, e.g., refs. [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29], see also [30] for a short review. The latter can be defined via a density-density correlation function:…”