Temperature dependence of low-lying electronic excitations of LaMnO3

M. A. Quijada, J. R. Simpson, L. Vasiliu-Doloc, J. W. Lynn, H. D. Drew, Y. M. Mukovskii, and S. G. Karabashev
Phys. Rev. B 64, 224426 – Published 26 November 2001
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Abstract

We report on the optical properties of undoped single crystal LaMnO3, the parent compound of the colossal magnetoresistive manganites. Near-normal-incidence-reflectance measurements are reported in the frequency range of 2050000cm1 and in the temperature range 10300K. The optical conductivity σ1(ω) is derived by performing a Kramers-Kronig analysis of the reflectance data. The far-infrared spectrum of σ1(ω) displays the infrared active optical phonons. While several of the phonons soften as the temperature is raised, no anomalies in the width or frequency of the phonons are observed at the Neel temperature of the sample (TN139K). The high-frequency σ1(ω) is characterized by the onset of absorption near 1.5 eV, a peak at 2 eV, and a second larger peak at 4 eV. The 2-eV feature has been identified as optical transitions across the Jahn-Teller split eg levels. The spectral weight of this feature increases in the low-temperature state. This implies a transfer of spectral weight from the UV to the visible region associated with the paramagnetic to antiferromagnetic state. We discuss the results in terms of the double-exchange processes that affect the optical processes in this magnetic material.

  • Received 29 March 2001

DOI:https://doi.org/10.1103/PhysRevB.64.224426

©2001 American Physical Society

Authors & Affiliations

M. A. Quijada1,*, J. R. Simpson1, L. Vasiliu-Doloc2,†, J. W. Lynn2, H. D. Drew1, Y. M. Mukovskii3, and S. G. Karabashev3

  • 1Materials Research Laboratory, Department of Physics, University of Maryland, College Park, Maryland 20742
  • 2NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899
  • 3Moscow Power Engineering Institute, Moscow, Russia

  • *Present address: GSFC-NASA, Code 551, Greenbelt, MD 20740. Email address: manuel.quijada@gsfc.nasa.gov
  • Present address: Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439.

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Vol. 64, Iss. 22 — 1 December 2001

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