Magneto-optical investigation of spin polarisation of La0. 7Ca0. 3MnO3 and La0. 7Sr0. 3MnO3

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Erscheinungsjahr:
2005
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Text
Beschreibung:
  • We investigate the ferromagnetic phase of thin epitaxial films of the CMR manganites and by temperature-dependent spectral generalised magneto-optical ellipsometry (SGME). The phase transitions from a paramagnetic insulator to a ferromagnetic metal take place at and , respectively. The measurements covering a spectral range of 0.5–5 eV are performed in the temperature range of 25–425 K. SGME allows a complete magneto-optical characterisation consisting of the determination of the diagonal components ɛ as well as the off-diagonal components ɛ of the dielectric tensor within a single measurement. Upon cooling through the Curie temperature, we observe the development of a Drude-like free-carrier response in ɛ, indicating the release of previously bound charges. Meanwhile, ɛ exhibits a rising magneto-optical response. This reflects, via the increasing degree of spin polarisation of the bands involved in optical transitions, the emergence of ferromagnetism. We tentatively assign spectral features between 2.5 and 4.5 eV to transitions involving the Mn-d shell, especially the and levels.
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  • info:eu-repo/semantics/closedAccess
Quellsystem:
Forschungsinformationssystem der UHH

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oai:www.edit.fis.uni-hamburg.de:publications/05b06537-feb2-4d9a-a9e3-e58791922768