Related papers: N\'eel and singlet RVB orders in the t-J model
The $t-J$ Hamiltonian is studied in a mean-field approximation by taking into account antiferromagnetic and d-wave pairing correlations. Considering the presence of antiferromagnetic fluctuations, the weaknesses of a mean-field…
We report the finding of time-reversal-symmetry-breaking $d_{x^2-y^2}+ id_{xy}$ superconducting ground state in the slave-boson mean-field theory for the t-J model on triangular lattice. For $t/J=-5$ ($t/J=-9$) pairing exists for $x < 13%$…
The N\'eel temperature, $T_{\rm N}$, of quasi-one- and quasi-two-dimensional antiferromagnetic Heisenberg models on a cubic lattice is calculated by Monte Carlo simulations as a function of inter-chain (inter-layer) to intra-chain…
We present a finite temperature ($T$) study of the t-J model on the two-dimensional triangular lattice for the negative hopping $t$, as relevant for the electron-doped Na$_x$CoO$_2$ (NCO). To understand several aspects of this system, we…
The N\'eel state in fermionic mixtures of two pseudospin species in an optical lattice is analyzed at low temperatures. Experimentally it remains a challenge to demonstrate antiferromagnetic correlations in ultracold fermionic quantum…
Spontaneous symmetry breaking is deeply related to dimensionality of system. The Neel order going with spontaneous breaking of $U(1)$ symmetry is safely allowed at any temperature for three-dimensional systems but allowed only at zero…
Implication of our recent proposal [J. Phys. Soc. Jpn. 65 (1996) 687] to treat large-amplitude gauge-field fluctuations around the slave-boson mean-field theory for the t-J model has been explored in detail. By attaching gauge flux to…
We study the magnetic properties of the $t-J$ model on triangular lattice in light of the recently discovered superconductivity in Na$_{x}$CoO$_{2}$ system. We formulate the problem in the Schwinger Boson - slave Fermion scheme and proposed…
The equal-time pairing correlation function of the two-dimensional t-J model on a square lattice is studied using a high-temperature expansion method. The sum of the pairing correlation, its spatial dependence, and the correlation length…
Effects of inhomogeneous doping on the high-$T_c$ cuprate superconductors are studied within the framework of the t-J model. Especially, the boundary between two non-superconducting regions with doping rates much higher and lower than the…
Magnetic and superconducting pairing correlation functions in a general class of Hubbard models, the t-J model and a single-band Hubbard model with additional bond-charge interaction are investigated, respectively. Some rigorous upper…
We study the t-J-$V$ model beyond mean field level at finite doping on the triangular lattice. The Coulomb repulsion $V$ between nearest neighbors brings the system to a charge ordered state for $V$ larger than a critical value $V_c$.…
Motivated by the recent discovery of superconductivity in two dimensional CoO$_2$ layers, we present some possibly useful results of the RVB mean field theory applied to the triangular lattice. Away from half filling, the order parameter is…
The pairing of quasiparticles in a CuO$_2$ plane is studied within a spin polaron formulation of the $t$-$t^{'}$-$J$ model. Our numerical solution of the Eliashberg equations unambiguously shows d-wave pairing between spin polarons on…
We analyze the high-temperature behavior of the susceptibilities towards a number of possible ordered states in the t-J-V model using the high-temperature series expansion. From all diagrams with up to ten edges, reliable results are…
Motivated by the recent discovery of superconductivity in Na$_x$CoO$_2\cdot y$H$_2$O, we use series expansion methods and cluster mean-field theory to study spontaneous charge order, Neel order, ferromagnetic order, dimer order and…
It remains an open question whether the two-dimensional single-band pure Hubbard model and its related pure $t$-$J$ model truly capture the superconducting order in cuprates. Recent numerical studies on this issue have raised a notable…
The nature of the cooperative Jahn-Teller (JT) transition accompanied by orbital order-disorder in Nd1-xCaxMnO3 has been studied by high temperature (300 - 1200K) synchrotron and laboratory X-ray powder diffraction in the low doping region…
A self-doped bilayer t-t'-J model of an electron- and a hole-doped planes is studied by the slave-boson mean-field theory. A hopping integral between the differently doped planes, which are generated by a site potential, are renormalized by…
The supersymmetric formulation of t-J model is studied in this paper at the mean-field level where $\delta$-T phase diagram is computed. We find that slave-fermion-like spiral phase is stable at low doping concentration, and the…