Coexistence of large and small polarons in manganites

Abstract

The interplay of the electron-phonon interaction and of the double and super exchange magnetic effects is analyzed in the $L{a}_{1-x}C{a}_{x}Mn{O}_3$ perovskites with $0<x<0.5$. By using an analytical variational scheme that allows to treat the electron-phonon interaction in a fully quantum manner it is shown that in the intermediate electron-phonon coupling regime a charge density instability occurs near the metal-insulator transition, induced by either temperature or hole doping. The system segregates in antiferromagnetic or paramagnetic small polarons and ferromagnetic large polarons domains characterized by different values of the lattice distortions that are satisfactory compared with those experimentally observed.

10 pages, 2 figures, to appear on Phys. Rev. B

References in corpus (3)

• Evidence for charge localization in the ferromagnetic phase of La_(1-x)Ca_(x)MnO_3 from High real-space-resolution x-ray diffraction
• A new variational approach for the Holstein Molecular Crystal Model
• Polaron features of the one-dimensional Holstein Molecular Crystal Model

Cited by in corpus (8)

• Ferromagnetism and electron-phonon coupling in the manganites
• Quantum Monte Carlo and variational approaches to the Holstein model
• Modelling of strain effects in manganite films
• Photoemission spectra of many-polaron systems
• Optical absorption and activated transport in polaronic systems
• Spectral properties and infrared absorption in manganites
• Polaron and bipolaron formation in the Hubbard-Holstein model: role of next-nearest neighbor electron hopping
• On the effects of the magnetic field and the isotopic substitution upon the infrared absorption of manganites