Charge localization and phonon spectra in hole-doped La<sub>2</sub>NiO<sub>4</sub>
R J McQueeney; A R Bishop; Ya-Sha Yi; Z G Yu
Журнал:
Journal of Physics: Condensed Matter
Дата:
2000-05-29
Аннотация:
The in-plane oxygen vibrations in La<sub>2</sub>NiO<sub>4</sub> are investigated for several hole-doping concentrations both theoretically and experimentally via inelastic neutron scattering. Using an inhomogeneous Hartree-Fock plus random-phase approximation numerical method in a two-dimensional Peierls-Hubbard model, it is found that the doping induces stripe ordering of localized charges, and that the strong electron-lattice coupling causes the in-plane oxygen modes to split into two subbands. This result agrees with the phonon band splitting observed by inelastic neutron scattering in La<sub>2-x</sub>Sr<sub>x</sub>NiO<sub>4</sub>. Predictions of strong electron-lattice coupling in La<sub>2</sub>NiO<sub>4</sub>, the proximity of both oxygen-centred and nickel-centred charge ordering, and the relation between charged stripe ordering and the splitting of the in-plane phonon band upon doping are emphasized.
96.21Кб