Related papers: Charge order and superconductivity in a two-dimens…
We study extended Hubbard model on a triangular lattice near doping $x=1/3$, which may be relevant for the recently discovered superconductor Na$_x$CoO$_2 \cdot y$H$_2$O. By generalizing this model to $N$ fermionic species, we formulate a…
Superconductivity was recently observed in boron-doped ($\sqrt{3}\times\sqrt{3}$)Sn/Si(111). The material can be described by an extended Hubbard model on a triangular lattice. Here, we use the random-phase approximation to investigate the…
Motivated by the recent numerical simulations for doped $t$-$J$ model on the honeycomb lattice, we study superconductivity of singlet and triplet pairing on the honeycomb lattice Hubbard model. We show that a superconducting state with…
To understand the microscopic mechanism of the charge order observed in the parent compound of the infinite-layer nickelate superconductors, we consider a minimal three-legged model consisting of a two-legged Hubbard ladder for the Ni…
We investigate the ground-state properties of the two-dimensional Hubbard model, based on the off-diagonal wave function variational Monte Carlo method. We use an optimized wave function that is improved from an initial one-body wave…
We have performed large-scale density-matrix renormalization group studies of the lightly doped Hubbard model on the honeycomb lattice on long three and four-leg cylinders. We find that the ground state of the system upon lightly doping is…
Combining the complementary capabilities of two of the most powerful modern computational methods, we find superconductivity in both the electron- and hole-doped regimes of the two-dimensional Hubbard model (with next nearest neighbor…
We study spin fluctuation (SF) mediated superconductivity (SC) in a half-filled square lattice Hubbard model with the transfer matrices -t between nearest neighbor sites and -t' between a half of next nearest neighbor sites neighboring…
The electronic orders in Hubbard models on a Kagome lattice at van Hove filling are of intense current interest and debate. We study this issue using the singular-mode functional renormalization group theory. We discover a rich variety of…
A half-filled-band Hubbard model on an anisotropic triangular lattice (t in two bond directions and t' in the other) is studied using an optimization variational Monte Carlo method, to consider the Mott transition and superconductivity…
Entanglement of charge orderings and other electronic orders such as superconductivity is in the core of challenging physics issues of complex materials including high temperature superconductivity. Here, we report on the observation of a…
The pairing symmetry in the electron mechanism for superconductivity is explored when charge fluctuations coexist with spin fluctuations. The extended Hubbard model is adopted to obtain, with the fluctuation exchange approximation, a phase…
The extended Hubbard model in the atomic limit, which is equivalent to lattice $S=1/2$ fermionic gas, is considered on the triangular lattice. The model includes onsite Hubbard $U$ interaction and both nearest-neighbor ($W_{1}$) and…
On the purpose of studying the effect of long-range Coulomb-interaction in strongly correlated electronic systems we bring in as its representative the nearest-neighbor repulsion ($v$) in addition to the on-site repulsion ($u$) and shall…
The possibility of charge order is theoretically examined for the Kondo lattice model in two dimensions, which does not include bare repulsive interactions. Using two complementary numerical methods, we find that charge order appears at…
The physical nature of doped Mott-insulator has been intensively studied for more than three decades. It is well known that the single band Hubbard model or $t$-$J$ model on the bipartite lattice is the simplest model to describe a doped…
Doped Hubbard model is a simple model for the high-Tc cuprate superconductors, while its ground state remains a challenge. Here, by performing state-of-the-art variational Monte Carlo calculations for the strong-coupling Hubbard model, we…
Charge ordering accompanied by lattice distortion in quasi-two dimensional organic conductors \theta-(ET)2X (ET=BEDT-TTF) is studied by using an extended Hubbard model with Peierls-type electron-lattice couplings within the Hartree-Fock…
The charge ordering phenomena in quasi two-dimensional 1/4-filled organic compounds (ET)_2X (ET=BEDT-TTF) are investigated theoretically for the $\theta$ and $\alpha$-type structures, based on the Hartree approximation for the extended…
Charge ordering in doped \cob planes near the commensurate fillings $x = {1/4}$ and 1/3 are considered for $Na_x CoO_2.yH_2O$ and suggested to be competitors to superconductivity, leading to the experimentally seen narrow superconducting…