Related papers: Flux period, spin gap, and pairing in the one-dime…
The spin-gap phase of the one-dimensional t-J-J' model is studied by the level-crossing of the singlet and the triplet excitation spectra. The phase boundary obtained between the Tomonaga-Luttinger and the spin-gap phases is remarkably…
We study the dependence of the ground state energy on an applied Aharonov-Bohm flux $\Phi$ for the Luttinger model with large momentum scattering. Employing the method of finite size bosonization, we show that for systems with a spin gap…
We use the coupled cluster method to high orders of approximation in order to calculate the ground-state energy, the ground-state magnetic order parameter, and the spin gap of the spin-1/2 J_1-J_2 model on the square lattice. We obtain…
The impact of the spin-flip terms on the (static and dynamic) charge and spin correlations in the Luttinger-liquid ground state of the 1D $t-J$ model is assessed by comparison with the same quantities in the 1D $t-J_z$ model, where…
The magnetic flux periodicity in superconducting loops is reviewed. Whereas quantization of the magnetic flux with hc/2e prevails in sufficiently thick loops with current free interior, the supercurrent in narrow loops is either hc/2e or…
We discuss the possible existence of a spin-gap phase in the low-doping regime of strongly-correlated two-dimensional electrons within the gauge field description of the t-J model. The spin-gap phase was recently shown by Ubbens and Lee to…
We investigate the spin-1/2 Heisenberg model on a rectangular lattice, using the Gutzwiller projected variational wave function known as the staggered flux state. Using Monte Carlo techniques, the variational parameters and static…
The recursion method is used to determine the T=0 spin dynamic structure factor S_{zz}(q,\omega) in the Luttinger liquid state and in the phase-separated state of the one-dimensional t-J model. As the exchange coupling increases from zero,…
We study the phase diagram of a one-dimensional extended Hubbard model with antiferromagnetic exchange interaction analytically and numerically. The bosonization and transfer-matrix renormalization group methods are used in the…
We investigate the phase diagram of the half-filled SU(N) Hubbard-Heisenberg model with hopping t, exchange J and Hubbard U, on a square lattice. In the large-N limit, and as a function of decreasing values of t/J, the model shows a…
We give the details of the analysis for critical properties of spin-gap phases in one-dimensional lattice electron models. In the Tomonaga-Luttinger (TL) liquid theory, the spin-gap instability occurs when the backward scattering changes…
We consider a strongly correlated "t,t'-J" spin model with a positive uniaxial anisotropy. We show that in 2+1 dimensions, this model is equivalent to spin-charge excitations coupled to Z_2 Ising gauge fields and not to a U(1) gauge fields…
We study the one-dimensional deformed $t-t^{\prime}-J$ model in terms of the continuum field theories. We found that at low doping concentration and far away from the phase separation regime, there are two phases: the Luttinger liquid and…
The quantum spin-1/2 antiferromagnetic Heisenberg model on a two dimensional triangular lattice geometry with spatial anisotropy is relevant to describe materials like ${\rm Cs_2 Cu Cl_4}$ and organic compounds like…
The spin and charge excitations of the t--J ladder are studied by exact diagonalization techniques for several electron densities. The various modes are classified according to their spin (singlet or triplet excitations) and their parity…
We study the one-dimensional supersymmetric t-J model with 1/r2 interaction threaded by magnetic flux. Because of the long range interaction, the effect of this flux leads to a modification of the electron hopping term. We present an exact…
We analyse the t-t'-t''-J model, relevant to the superconducting cuprates. By using chiral perturbation theory we have determined the ground state to be a spiral for small doping \delta << 1 near half filling. In this limit the solution…
We investigate the ground-state properties of the spin-half $J_1{-}J_2$ Heisenberg chain with a next-nearest-neighbor spin-Peierls dimerization using conformal field theory and Lanczos exact diagonalizations. In agreement with the results…
We propose a correlated spin-singlet-pairs wave function to describe the spin-gap phase of the one-dimensional $t-J$ model at low density. Adding a Jastrow factor with a variational parameter, $\nu$, first introduced by Hellberg and Mele,…
We consider an exchange model describing two isotropic spin-1/2 Heisenberg antiferromagnets coupled by a quartic term on the square lattice. The model is relevant for systems with orbital degeneracy and strong electron-vibron coupling in…