Related papers: Doping dependence of charge dynamics in electron-d…
We study a two-dimensional t-J model close to the Ising limit in which charge inhomogeneity is stabilized by an on-site potential e_s, by using diagonalization in a restricted Hilbert space and finite temperature Quantum Monte Carlo. Both…
A detailed exact-diagonalization study is made for the doping dependence of the single-particle spectral function $A({\bf k},\omega)$ and momentum distribution function $n({\bf k})$ of the two-dimensional $t$$-$$J$ model as a representative…
The pseudogap phenomena in High-$T_{{\rm c}}$ cuprates are investigated on the basis of the Hubbard model which includes only the on-site repulsive interaction $U$. We consider the pairing scenario for the pseudogap. The pseudogap arises…
Thermodynamic quantities are derived for superconducting and pseudogap regimes by taking into account both amplitude and phase fluctuations of the pairing field. In the normal (pseudogap) state of the underdoped cuprates, two domains have…
The cuprates seem to exhibit statistics, dimensionality and phase transitions in novel ways. The nature of excitations [i.e. quasiparticle or collective], spin-charge separation, stripes [static and dynamics], inhomogeneities, psuedogap,…
We study the evolution of the optical conductivity in the t-J model with temperature and doping using the Extended Dynamical Cluster Approximation. The cluster approach results in an optical mass which is doping independent near half…
Finite-temperature properties of weakly doped antiferromagnets as modeled by the two-dimensional t-J model and relevant to underdoped cuprates are investigated by numerical studies of small model systems at low doping. Two numerical methods…
We study the effects of hole doping on one-dimensional Mott insulators with orbital degrees of freedom. We describe the system in terms of a generalized t-J model. At a specific point in parameter space the model becomes integrable in…
Using a doping-determined multiband model spectrum of a "typical'' cuprate the effective mass of the paired carriers is calculated on the whole doping scale. Large $m_{ab}$ values quench rapidly with leaving the very underdoped region.…
Magnetic correlations of doped Mott insulators hold the key to the unusual characteristics of many quantum materials. Recent experiments with ultracold atoms in optical lattices have provided new information about the magnetic properties of…
Infrared reflectance measurements were made with light polarized along the a- and c-axis of both superconducting and antiferromagnetic phases of electron doped Nd$_{1.85}$Ce$_{.15}$CuO$_{4+\delta}$. The results are compared to…
In the hole-doped cuprate superconductors, the superconducting transition temperature $T_c$ exhibits a dome-like feature against the doping rate. By contrast, recent experiments reveal that $T_c$ in the electron-doped systems monotonically…
We present a coherent scenario for the physics of cuprate superconductors, which is based on a charge-driven inhomogeneity, i.e. the ``stripe phase''. We show that spin and charge critical fluctuations near the stripe instability of…
Doping and disorder are inseparable in the superconducting cuprates. Assuming the simplest possible disordered doping, we construct a semiphenomenological model and analyze its experimental consequences. Among the affected experimental…
We study a simple BCS-like model which describes unconventional superconductivity on the basis of an electron-electron attraction corresponding to the delta-shell potential: $U(r) = -g \delta(r-r_0)$. It predicts a $T_c$ vs. doping behavior…
We review a recently proposed mechanism for superconductivity in hole-doped cuprates exhibiting a strong interplay between pairing and antiferromagnetism. Starting from the t-t'-J model for the CuO planes, we show that this interplay can…
We present reliable many-body calculations for the t-t'-t''-U Hubbard model that explain in detail the results of recent angle-resolved photoemission experiments on electron-doped high-temperature superconductors. The origin of the…
The dependence of the superconducting gaps in epitaxial Ba(Fe_{1-x}Co_{x})_2As_2 thin films on the nominal doping x (0.04 \leq x \leq 0.15) was studied by means of point-contact Andreev-reflection spectroscopy. The normalized conductance…
It is suggested that recent experiments provide evidence for modulations along the charged stripes in the striped phase of the cuprates. Furthermore, 1/8 doping is special because it is associated with a crossover: for lower doping the…
The next-nearest-neighbour hopping term t' is shown to stabilize the AF state of the doped Hubbard model with respect to transverse perturbations in the order- parameter by strongly suppressing the intraband particle-hole processes. For a…