2001/08/14 by N. N. Kovaleva, J. L. Gavartin, Jacob Gavartin +4 · 2 citations
Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Electronic and Structural Properties of Oxides #Magnetic and transport properties of perovskites and related materials #cond-mat.str-el
paper · pdf · doi:10.1134/1.1448620
published as JETP 94, 178 (2002). · 18 pages, 6 figures, it was presented partially at SCES-2001 conference in Ann Arbor, Michigan
arxiv created 2001/08/14 · openalex publication_date 2002/01/01 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/30
We explore the role of electronic and ionic polarization energies in the physics of “colossal” magnetoresistive (CMR) materials. We use the Mott-Littleton approach to evaluate polarization energies in the LaMnO 3 lattice associated with holes localized on both the Mn 3+ cation and the O 2− anion. The full (electronic and ionic) lattice relaxation energy for a hole localized at the O site is estimated at 2.4 eV, which is appreciably greater than that of 0.8 eV for a hole localized at the Mn site, indicating a strong electron-phonon interaction in the former case. The ionic relaxation around the localized holes differs for anion and cation holes. The relaxation associated with Mn 4+ is approximately isotropic, whereas ionic displacements around O − holes show axial symmetry with the axis directed towards the apical oxygens. Using the Born-Haber cycle, we examine thermal and optical energies of the hole formation associated with the electron ionization from Mn 3+ , O 2− , and La 3+ ions in the LaMnO 3 lattice. For these calculations, we derive a phenomenological value for the second electron affinity of oxygen in the LaMnO 3 lattice by matching the optical energies of the La 4+ and O − hole formation with maxima of binding energies in the experimental photoemission spectra. The calculated thermal energies predict that the electronic hole is marginally more stable in the Mn 4+ state in the LaMnO 3 host lattice, but the energy of a hole in the O − state is only higher by a small amount, 0.75 eV, suggesting that both possibilities should be treated seriously. We examine the energies of a number of fundamental optical transitions, as well as those involving self-trapped holes of Mn 4+ and O − in the LaMnO 3 lattice. The reasonable agreement of our predicted energies, linewidths, and oscillator strengths with experimental data leads us to plausible assignments of the optical bands observed. We deduce that the optical band near 5 eV is associated with the O(2 p )-Mn(3 d ) transition of a charge-transfer character, whereas the band near 2.3 eV is rather associated with the presence of Mn 4+ and/or O − self-trapped holes in the nonstoichiometric LaMnO 3 compound.