Dimerization in a Half-Filled One-Dimensional Extended Hubbard Model

Abstract

We use a density matrix renormalization group method to study quantitatively the phase diagram of a one-dimensional extended Hubbard model at half-filling by investigating the correlation functions and structure factors. We confirm the existence of a novel narrow region with long-rang bond-order-wave order which is highly controversial recently between the charge-density-wave phase and Mott insulator phase. We determined accurately the position of the tricritical point U t ≃ 7.2t, V t ≃ 3.746t which is quite different from previous studies.

Unconventional superconducting phases for the two-dimensional extended Hubbard model on a square lattice

“…4,5 Recent identification of the bond charge-density wave instability between charge-and spin-density wave phases, at weak and strong interactions, completes the phase diagram of this model. [6][7][8][9][10][11] Meanwhile, in a two-leg ladder, a checkerboard charge-ordered state has been proposed for all fillings between quarter and half, with on-site and nearest-neighbor repulsion. 12 Its application to the coupled quarter-filled ladders with coupling to the lattice has recently been studied 13 to explain the spin gaps in the NaV 2 O 5 material.…”

Population imbalance in the extended Fermi-Hubbard model

“…The third term takes into account the interaction between fermions on nearest neighboring sites. The above Hamiltonian at half filling has been extensively studied before, and a rich phase diagram has been reported to exist, with different correlators characterizing the respective phases [9,[13][14][15][16][17][18].…”

“…In contrast, we do not intend to evaluate the entire phase diagram. Instead, we select representative points from deep inside various phases extracted from the phase diagrams of EHM in the balanced case reported earlier in the literature [9,[13][14][15][16]18].…”

“…We now turn our attention to the evaluation of the pair correlation function in the singlet and triplet superfluid (SSF and TSF) phases as reported earlier in the literature [9,[13][14][15][16]18], defined as ρ Figs. 3(a) and 3(c).…”

“…On the other hand, different types of interactions can compete resulting in structure formation in nature [7,8]. Long-range interactions, in particular, induce a miscellany of phases in fermionic systems such as charge density wave (CDW), spin-density wave (SDW), bond-order wave (BOW), phase separated (PS), singlet superfluid (SSF), and triplet superfluid (TSF) phases [9][10][11][12][13][14][15][16][17][18]. In addition, it introduces a nontrivial structure in the system, one particularly being the subtle hidden order which is revealed by highly nonlocal string correlation functions.…”