paper

Infrared response of ordered polarons in layered perovskites

arXiv:cond-mat/9609123 · doi:10.1103/PhysRevB.54.R9592

Abstract

We report on the infrared absorption spectra of three oxides where charged superlattices have been recently observed in diffraction experiments. In La $_{1.67}$ Sr $_{0.33}$ NiO $_{4}$ , polaron localization is found to suppress the low-energy conductivity through the opening of a gap and to split the $E_{2 u}$ - $A_{2 u}$ vibrational manifold of the oxygen octahedra. Similar effects are detected in Sr $_{1.5}$ La $_{0.5}$ MnO $_{4}$ and in La $_{2}$ NiO $_{4 + y}$ , with peculiar differences related to the type of charge ordering.

File latex, 11 p. + 3 Figures, to appear on Phys. Rev. B (Rapid Commun.), 1 Oct. 1996. The figures will be faxed upon request. E-mail:[email protected] Fax: +39-6-4463158