Charge-Density-Excitation Spectrum in the t-t'-J-V Model

ANDRÉS GRECO; YAMASE, HIROYUKI; MATÍAS BEJAS

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN

PHYSICAL SOC JAPAN

Año: 2017 vol. 86 p. 1 - 5

0031-9015

We study the density-density correlation function in a large-N scheme of thet-t´-J-V model. When the nearest-neighbor Coulomb interaction V is zero, ourmodel exhibits phase separation in a wide doping region and we obtain largespectral weight near momentum q=(0,0) at low energy, which originates from theproximity to phase separation. These features are much stronger for electrondoping than for hole doping. However, once phase separation is suppressed byincluding a finite V, the low-energy spectral weight around q=(0,0) issubstantially suppressed. Instead a sharp zero-sound mode is stabilized abovethe particle-hole continuum. We discuss that the presence of a moderate valueof V, which is frequently neglected in the t-J model, is important tounderstand low-energy charge excitations especially close to q=(0,0) forelectron doping. This insight should be taken into account in a future study ofx-ray scattering measurements.