ISSN:
1063-7834
Source:
Springer Online Journal Archives 1860-2000
Topics:
Physics
Notes:
Abstract To study the band structure and carriers in lanthanum manganites, measurements have been made of the reflectance spectra of single crystals and polycrystals in the 0.04–1.6-eV range and of the optical conductivity σ opt calculated by the Kramers-Kronig method as functions of the concentration and species of divalent ions in the paramagnetic (PM) and ferromagnetic (FM) regions. The optical gap for single-crystal La0.9Sr0.1MnO3 is ∼0.17 eV, and the polaronband energy is 0.12 eV. In the PM region, σ opt spectra do not indicate a band-carrier contribution, and conduction is dominated by polaron hopping and activation to the mobility edge. In the FM region, the variation in the σ opt and absorption spectra of La0.7Sr0.3MnO3 epitaxial films indicate the appearance of band carriers and a red shift of the absorption edge. The two band-carrier contributions, with weak and strong dependences on photon energy, are related to conduction in the antiferromagnetic matrix and the ferromagnetic regions.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1134/1.1130796
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