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Título:
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Dielectric response to the low-temperature magnetic defect structure and spin state transition in polycrystalline LaCoO_(3)
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Autores:
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Schmidt, Rainer ;
Wu, J. ;
Leighton, C. ;
Terry, I.
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Tipo de documento:
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texto impreso
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Editorial:
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American Physical Society, 2009-03
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Dimensiones:
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application/pdf
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Nota general:
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info:eu-repo/semantics/openAccess
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Idiomas:
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Palabras clave:
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Estado = Publicado
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Materia = Ciencias: Física: Electricidad
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Materia = Ciencias: Física: Electrónica
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Tipo = Artículo
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Resumen:
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The dielectric and magnetic properties and their correlations were investigated in polycrystalline perovskite LaCoO_(3). The intrinsic bulk and grain-boundary (GB) dielectric relaxation processes were deconvoluted using impedance spectroscopy between 20 and 120 K, and resistivity and capacitance were analyzed separately. A thermally induced magnetic transition from a Co^(3+) low-spin (LS) (S=0;t^(6)_(2g)e^(0)_(g)) to a higher spin state occurs at T_(s1) ? 80 K, which is controversial in nature and has been suggested to be an intermediate-spin (IS) state (S=1;t^(5)_(2g)e^(1)_(g)) or a high-spin(HS) state (S=2;t^(4)_(2g)e^(2)_(g)) transition. This spin state transition was confirmed by magnetic-susceptibility measurements and was reflected in the impedance by a split of the single GB relaxation process into two coexisting contributions. This apparent electronic phase coexistence at T > 80 K was interpreted as a reflection of the coexistence of magnetic LS and IS/HS states. At lower temperatures (T ? 40 K) perceptible variation in bulk dielectric permittivity with temperature appeared to be correlated with the magnetic susceptibility associated with a magnetic defect structure. At 40 K
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En línea:
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https://eprints.ucm.es/id/eprint/32655/1/Schmidt07bis.libre.pdf
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