Powered by Indico
v3.2.8
Description:Speaker:
Natanael de Carvalho Costa, UFRJ
Title:
Properties of the two-dimensional Hubbard-Holstein model
Abstract:
The electron-electron (e-e) and electron-phonon (e-ph) interactions play an important role in correlated materials, being key features for spin, charge, and pair correlations. Thus, here we investigate their effects in strongly correlated systems by performing unbiased quantum Monte Carlo simulations for the Hubbard-Holstein model at the half-filling of 2D lattices. Starting with the square lattice, we study the competition and interplay between antiferromagnetism (AFM) and charge-density wave (CDW), establishing its very rich phase diagram. In the region between AFM and CDW phases, we have found an enhancement of superconducting pairing correlations, favoring (nonlocal) s-wave pairs [1]. Similarly, we determine semimetal-to-insulator quantum critical points in the honeycomb lattice, by performing careful finite-size scaling analysis. In this case, we notice that the AFM and CDW critical lines have a strong dependence on phonon frequencies, in particular when the e-e and e-ph couplings are equal. Finally, we also examine the critical exponents, which seem to be consistent with those from Gross-Neveu models [2]. Our findings represent a complete description of the model, and may shed light on the emergence of many-body properties in such systems.
[1] N. C. Costa, K. Seki, S. Yunoki, and S. Sorella, Phase diagram of the two-dimensional Hubbard-Holstein model, Commun. Phys. 3, 80 (2020).
[2] N. C. Costa, K. Seki, and S. Sorella, Magnetism and Charge Order in the Honeycomb Lattice, Phys. Rev. Lett. 126, 107205 (2021).