Anomalous spin and charge dynamics of the t-J model at low doping

Correlation-induced Suppression of Bilayer Splitting in High-Tc Cuprates: A Variational Cluster Approach

We carry out a theoretical study of the bilayer single-band Hubbard model in the undoped and in the superconducting phases by means of the variational cluster approach. In particular, we focus on the splitting between the "bonding" and "antibonding" bands induced by the interlayer hopping, as well as its interplay with strong correlation effects. We find that the splitting is considerably suppressed in both the normal and superconducting phases, in qualitative agreement with experiments on Bi2Sr2CaCu2O8+δ . In addition, in the superconducting phase, the shape of the splitting in k space is modified by correlations.

Momentum dependence of charge excitations in the electron-doped superconductor Nd1.85 Ce0.15 CuO4: a resonant inelastic x-ray scattering study

We report a resonant inelastic x-ray scattering (RIXS) study of charge excitations in the electron-doped high-T(c) superconductor Nd1.85 Ce0.15 CuO4. The intraband and interband excitations across the Fermi energy are separated for the first time by tuning the experimental conditions properly to measure charge excitations at low energy. A dispersion relation with q-dependent width emerges clearly in the intraband excitation, while the intensity of the interband excitation is concentrated around 2 eV near the zone center. The experimental results are consistent with theoretical calculation of the RIXS spectra based on the Hubbard model.