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Infrared reflectivity investigation of the phase transition sequence in Pr0.5Ca0.5MnO3

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Resumo:This work reports an infrared reflectivity study of the phase transition sequence observed in Pr0.5Ca0.5MnO3. The need to measure over an extended spectral range in order to properly take into account the effects of the high frequency polaronic absorption is circumvented by adopting a simple approximate method, based on the asymmetry present in the Kramers Kronig inversion of the phonon spectrum. The temperature dependence of the phonon optical conductivity is then investigated by monitoring the behavior of three relevant spectral moments of the optical conductivity.This combined methodology allows us to disclose subtle effects of the orbital,charge and magnetic orders on the lattice dynamics of the compound.The characteristic transition temperatures inferred from the spectroscopic measurements are compared and correlated with those obtained from the temperature dependence of the induced magnetization and electrical resistivity.
Autores principais:Ribeiro, José Luís Pires
Outros Autores:Vieira, L. G.; Gomes, I. T.; Araujo, J. P.; Tavares, P.; Almeida, B. G.
Assunto:Ferromagnetism and anti-ferromagnetism Orbital order Spin-lattice coupling Optical conductivity Infrared spectroscopy
Ano:2016
País:Portugal
Tipo de documento:artigo
Tipo de acesso:acesso restrito
Instituição associada:Universidade do Minho
Idioma:inglês
Origem:RepositóriUM - Universidade do Minho
Descrição
Resumo:This work reports an infrared reflectivity study of the phase transition sequence observed in Pr0.5Ca0.5MnO3. The need to measure over an extended spectral range in order to properly take into account the effects of the high frequency polaronic absorption is circumvented by adopting a simple approximate method, based on the asymmetry present in the Kramers Kronig inversion of the phonon spectrum. The temperature dependence of the phonon optical conductivity is then investigated by monitoring the behavior of three relevant spectral moments of the optical conductivity.This combined methodology allows us to disclose subtle effects of the orbital,charge and magnetic orders on the lattice dynamics of the compound.The characteristic transition temperatures inferred from the spectroscopic measurements are compared and correlated with those obtained from the temperature dependence of the induced magnetization and electrical resistivity.