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Magnetic, electronic, dielectric and optical properties of Pr(Ca:Sr)MnO 3 |
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| Authors: | J Sichelschmidt M Paraskevopoulos M Brando R Wehn D Ivannikov F Mayr K Pucher J Hemberger A Pimenov H-A Krug von Nidda P Lunkenheimer VYu Ivanov AA Mukhin AM Balbashov A Loidl |
| Institution: | Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany, DE Experimentalphysik V, Universit?t Augsburg, 86135 Augsburg, Germany, DE General Physics Institute, Russian Academy of Sciences, 105835 Moscow, Russia, RU Moscow Power Engineering Institute, 105835 Moscow, Russia, RU |
| Abstract: | The charge-ordered perovskite Pr0.65Ca0.28Sr0.07MnO3 was investigated by means of magnetic susceptibility, specific heat, dielectric and optical spectroscopy and electron-spin resonance techniques. Under moderate magnetic fields, the charge order melts yielding colossal magnetoresistance effects with changes of the resistivity over eleven orders of magnitude. The optical conductivity is studied from audio frequencies far into the visible spectral regime. Below the phonon modes hopping conductivity is detected. Beyond the phonon modes the optical conductivity is explained by polaronic excitations out of a bound state. ESR techniques yield detailed informations on the (H,T ) phase diagram and reveal a broadening of the linewidth which can be modeled in terms of activated polaron hopping. Received 9 August 2000 |
| Keywords: | PACS 63 20 -e Phonons in crystal lattices – 71 30 +h Metal-insulator transitions and other electronic transitions – 72 60 +g Mixed conductivity and conductivity transitions – 78 30 -j Infrared and Raman spectra |
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